Remove Python 3.7 (EOL since EOL since 2023-06-27) from CI

[kiendang]

https://devguide.python.org/versions/

[sjdemartini]

Cool, LGTM!

One comment: we may want to change the pre-commit pyupgrade arg to use --py38-plus now instead of py37:

graphene-django/.pre-commit-config.yaml

Line 22 in 8540a93

args: [--py37-plus]

That could presumably be a separate PR after this, since we'll likely want to re-run it on all existing files to upgrade any syntax that was kept around in support of 3.7.

[kiendang]

Good catch! We could also take this opportunity to switch to ruff? Ruff implements both pyupgrade and flake8 which we use in our pre-commit.

[sjdemartini]

Yeah great suggestion. I'm using ruff instead of pyupgrade, flake8, etc in a project of mine, and I'm a big fan!

[kiendang]

@sjdemartini I just include the change to --py38-plus here since after running pre-commit there's no change.
I was looking into changing to ruff but it's a bit more involved since we need to migrate the flake8 and isort config in setup.cfg so will leave to a future PR.