Test Python 3.11 on Linux, Windows and Mac, add 3.12-dev

[kohtala]

Update tests for 3.11 and 3.12-dev. Update dependencies since flake8 was not compatible with Python 3.12.

Only after making the changes, I noticed there was already #329. Since there has been no release since, I anyway create this pull request in hopes it'll help get the release with 3.11 support sooner rather than later.

• fixes Wheel for Python 3.11 #327

Checklist:

• Add tests that demonstrate the correct behavior of the change. Tests should fail without the change.
• Add or update relevant docs, in the docs folder and in code.
• Add an entry in CHANGES.rst summarizing the change and linking to the issue.
• Add .. versionchanged:: entries in any relevant code docs.
• Run pre-commit hooks and fix any issues.
• Run pytest and tox, no tests failed.

[davidism]

#345