This is a mechanical change. I spotted `Currerntly` while reading the
docs, the ran the codebase through the `typos` and `codespell` tools.

I two typos reported by the tools: "unparseable" (because it's a valid
alternative spelling to "unparsable") and "dependant" (because it would
become an API change).

* `applicaton` -> `application`
* `Currerntly` -> `Currently`
* `didnt` -> `didn't`
* `enpoint` -> `endpoint`
* `existense` -> `existence`
* `incoveniences` -> `inconveniences`
* `indepent` -> `independent`
* `Insteaad` -> `Instead`
* `intructions` -> `instructions`
* `overriden` -> `overridden`
* `unparseable` -> `unparsable`

> [!NOTE]
>
> This resolves a warning currently thrown in CI ([recent
example](https://github.com/zmievsa/cadwyn/actions/runs/12256876257)):
>
>
![image](https://github.com/user-attachments/assets/4ff8ee98-855a-4116-91b5-e2fccb75e179)


`actions/upload-artifact` v3 and `actions/download-artifact` v3 [will be
disabled on
2025-01-31](https://github.blog/changelog/2024-04-16-deprecation-notice-v3-of-the-artifact-actions/).

The only change from v3 to v4 that affects this workflow is that
artifacts with the same name can only be overwritten, so the artifact
names must now be unique.

Merging now happens at download, not at upload, so this commit modifies
the Python and docs test artifact names to share the same prefix and
downloads them all in one shot.

This resolves warnings in CI that two actions use Node.js 16 and must be
upgraded to versions that use Node.js 20 ([recent
example](https://github.com/zmievsa/cadwyn/actions/runs/8683445478)).

Would you be interested in a PR to configure Dependabot to monitor for
updates to action versions on a monthly basis?

Co-authored-by: Stanislav Zmiev <zmievsa@gmail.com>

I overlooked this change in #235, and that PR didn't change files that
would have triggered the CI test suite to run.

So, in addition, this PR modifies `ci.yaml` so that changes to that file
trigger the workflow, too.

Co-authored-by: Stanislav Zmiev <zmievsa@gmail.com>

Older starlette and pydantic syntax is currently supported, so these
warnings are known and expected.

There are still two `ResourceWarning`s from anyio left to address. These
are thrown due to unclosed `MemoryObjectReceiveStream` objects.

Co-authored-by: Stanislav Zmiev <zmievsa@gmail.com>

This commit introduces the following change:

* Configure pytest to escalate warnings to errors.
* Ignore a `ResourceWarning` caused by starlette.

starlette opens an anyio object without closing it; there are several
open and merged PRs about this problem but no open issues to link to.

Spotted this while reviewing some docs.