Type-check on Python 3.12

[Avasam]

Summary of changes

Actually type-check targeting all Python versions in CI, including 3.12

I'd rather if it was possible for the CI to tell mypy which python version to target to override python_version config.

Pull Request Checklist

• [x] Changes have tests (these are the test changes)
• [x] News fragment added in newsfragments/. (not public-facing) (See documentation for details)

[Avasam]

I'm gonna leave this one for later. I won't have a choice but to tackle it to merge setuptools stubs from typeshed, but it doesn't affect pkg_resources which I'm focusing on for now.

[Avasam]

Looks like I'll have to handle a handful of the typeshed-related TODOs first. Because distutils imports become Any in Python 3.12, a handful of type-ignores become unused.

[Avasam]

Hopefully I didn't forget to add anything to typeshed. Waiting for https://github.com/python/mypy/issues/17285

[abravalheri]

Thank you very much, @Avasam.