docs: improve python and venv setup instructions in CONTRIBUTING.md (#791)

* docs: refer to pyenv in CONTRIBUTING.md

This commit was made in order to account for users who may already have
a Python installation that isn't 3.12.

A good real world scenario where this may be a problem is users running
on rolling release Linux distributions, such as Arch Linux which
provides bleeding edge updates in a weekly basis.

Continuing with Arch Linux as an example, it provides Python 3.13, which
the current version of TagStudio doesn't seem to work with, an issue I
encountered myself this morning.

In some systems like Windows, this may not matter, but it is an issue
nonetheless, and users using a package manager centric system can't be
expected to downgrade/upgrade their Python version for TagStudio, as
this may cause issues in their system.

The easiest way to solve this is with pyenv, which enables users to
install other Python versions independent from each other, aside from
the system install, and allows specifying a version to use for a
directory (And its subdirectories), the current terminal session, or the
entire system if desired.

Here is a short, technical and objective summary of the changes:
- Updated `.gitignore` to to ignore `.python-version` which pyenv uses.
- Updated CONTRIBUTING.md to refer to pyenv for versioning issues.
    - pyenv is listed as a prerequisite, specifying in parenthesis that it's only for when your Python install isn't 3.12.
    - The "Creating a Python Virtual Environment" section now has an additional step at the beginning, to check that the current Python installation is 3.12.
        - As part of this added step, there are steps to use pyenv to install Python 3.12 separately from the existing Python installation, and activate it for the TagStudio root folder, in case it's not the appropriate version.
    - The numbering of the other steps was offset accordingly.
    - The "Manually Launching (Outside of an IDE)" section now refers to the above first step, should the user encounter some kind of error.

* docs: refer to alternate shells in CONTRIBUTING.md

Some users may not be using the default shell for their system, and
Linux users are the most likely to do this, though this can be seen in
macOS as well. People will often use shells like fish which is not POSIX
compliant but works very well and has great auto-completion, it's very
user friendly.

The reason why I care about this is that the instructions specify to use
.venv/bin/activate which is a bash script and will not run on fish or
csh, and if you take a look at the script, indeed it says it will only
run with bash.

Python will provide alternate scripts for other shells, and at least on
my system (CachyOS), those are scripts for Powershell, bash, fish and
csh. People using these alternate shells, who don't know this may be
confused when running the script referenced in CONTRIBUTING.md and
seeing it fail completely.

The only real change in this commit was adding under the "Linux/macOS"
command in step 3 (step 2 prior to my last commit) of the "Creating a
Python Virtual Environment" section, a short instruction to switch to
the default shell, or use the appropriate script for the user's
preferred shell if any (Since, at least on my system, there aren't
scripts for every shell, for example there is no activate.zsh file).

* fix: modal windows now have the Qt.Dialog flag

Set the Qt.Dialog flag for modal windows, such as "Add Field" so that
they will be seen as dialogs in the backend. This change is unlikely to
be at all noticeable in systems like Windows, but for users running
tiling window managers like bspwm or Sway, this will prevent these modal
windows from being tiled alongside the main window, instead they will be
floating on top, which is the expected behaviour seen on floating window
managers, like the ones used by Windows and macOS.

Added self.setWindowFlag(Qt.Dialog, on=True) # type: ignore to the
following files:
- tagstudio/src/qt/modals/add_field.py
- tagstudio/src/qt/modals/delete_unlinked.py
- tagstudio/src/qt/modals/drop_import.py
- tagstudio/src/qt/modals/file_extension.py
- tagstudio/src/qt/modals/fix_dupes.py
- tagstudio/src/qt/modals/fix_unlinked.py
- tagstudio/src/qt/modals/folders_to_tags.py
- tagstudio/src/qt/modals/mirror_entities.py
- tagstudio/src/qt/widgets/paged_panel/paged_panel.py
- tagstudio/src/qt/widgets/panel.py
- tagstudio/src/qt/widgets/progress.py

Note that without adding # type: ignore, MyPy *will* give out an error,
presumably because PySide6 is missing type hints for several things, and
this may *or* may not be a justifiable use of # type: ignore, which
throws the MyPy type checking for that line out the window.

Ref: #392, #464

* fix: I forgot to run ruff format

* revert: changes to docs and gitignore

This revert is for moving the referenced changes to their own pull request.

Refs: 15f4f38, a25ef8c

* docs: other shells and pyenv in CONTRIBUTING.md

This commit changes CONTRIBUTING.md to refer to pyenv in the case of
issues with Python versions, as well as downloading the correct version
off of the Python website alternatively. It also now elaborates on the
process of running the Python virtual environment on Linux and macOS, by
referencing activation scripts for alternative shells such as fish and
CSH.

The table added to CONTRIBUTING.md is taken from the official Python
documentation: https://docs.python.org/3.12/library/venv.html

* revert: accidental inclution of #464

Refs: a51550f, 5854ccc

Author: ChloeZamorano

.gitignore

@@ -88,9 +88,7 @@ profile_default/
 ipython_config.py
 
 # pyenv
-#   For a library or package, you might want to ignore these files since the code is
-#   intended to run in multiple environments; otherwise, check them in:
-# .python-version
+.python-version
 
 # pipenv
 #   According to pypa/pipenv#598, it is recommended to include Pipfile.lock in version control.

CONTRIBUTING.md

@@ -44,15 +44,30 @@ If you wish to launch the source version of TagStudio outside of your IDE:
 > [!TIP]
 > On Linux and macOS, you can launch the `tagstudio.sh` script to skip the following process, minus the `requirements-dev.txt` installation step. _Using the script is fine if you just want to launch the program from source._
 
-1. In the root repository directory, create a python virtual environment:  
+1. Make sure you're using the correct Python version:
+   -   If the output matches `Python 3.12.x` (where the x is any number) then you're using the correct Python version and can skip to step 2. Otherwise, you can install the correct Python version from the [Python](https://www.python.org/downloads/) website, or you can use a tool like [pyenv](https://github.com/pyenv/pyenv/) to install the correct version without changes to your system:
+      1. Follow pyenv's [install instructions](https://github.com/pyenv/pyenv/?tab=readme-ov-file#installation) for your system.
+      2. Install the appropriate Python version with pyenv by running `pyenv install 3.12` (This will **not** mess with your existing Python installation).
+      3. Navigate to the repository root folder in your terminal and run `pyenv local 3.12`.
+      - You could alternatively use `pyenv shell 3.12` or `pyenv global 3.12` instead to set the Python version for the current terminal session or the entire system respectively, however using `local` is recommended.
+
+2. In the root repository directory, create a python virtual environment:  
    `python3 -m venv .venv`
-2. Activate your environment:
+3. Activate your environment:
 
 -   Windows w/Powershell: `.venv\Scripts\Activate.ps1`
 -   Windows w/Command Prompt: `.venv\Scripts\activate.bat`
 -   Linux/macOS: `source .venv/bin/activate`
+       Depending on your system, the regular activation script *might* not work on alternative shells. In this case, refer to the table below for supported shells:
+       |Shell   |Script                   |
+       |-------:|:------------------------|
+       |Bash/ZSH|`.venv/bin/activate`     |
+       |Fish    |`.venv/bin/activate.fish`|
+       |CSH/TCSH|`.venv/bin/activate.csh` |
+       |PWSH    |`.venv/bin/activate.ps1` |
+       
 
-3. Install the required packages:
+4. Install the required packages:
 
 -   `pip install -r requirements.txt`
 -   If developing (includes Ruff and Mypy): `pip install -r requirements-dev.txt`
@@ -61,6 +76,8 @@ _Learn more about setting up a virtual environment [here](https://docs.python.or
 
 ### Manually Launching (Outside of an IDE)
 
+If you encounter errors about the Python version, or seemingly vague script errors, [pyenv](https://github.com/pyenv/pyenv/) may solve your issue. See step 1 of [Creating a Python Virtual Environment](#creating-a-python-virtual-environment).
+
 -   **Windows** (start_win.bat)
 
     -   To launch TagStudio, launch the `start_win.bat` file. You can modify this .bat file or create a shortcut and add one or more additional arguments if desired.