Add support for Python 3.12

[hugovk]

The Python 3.12 release candidate is out! 🚀

Call to action

We strongly encourage maintainers of third-party Python projects to prepare their projects for 3.12 compatibilities during this phase, and where necessary publish Python 3.12 wheels on PyPI to be ready for the final release of 3.12.0.

See also https://dev.to/hugovk/help-test-python-312-beta-1508/

[chenrui333]

cc @tartley

[tartley]

cc @tartley

Amazing, nice work people!

[tartley]

cc @tartley

Amazing, nice work people!

Ah, I see there are failing tests, and I'm going to assume they are not caused by this branch. I'll take a look at the weekend, see if I can hit 'merge' in this when it's done...

[hugovk]

I've fixed the lint_python job, it was a codespell typo.

The other failures are unrelated to this PR, and are because GitHub Actions has dropped support for Python 2.7 as it's been EOL for so long (nearly 4 years!):

Warning: The support for python 2.7 will be removed on June 19. Related issue: actions/setup-python#672
Version ~2.7.0-0 was not found in the local cache
Error: The version '2.7' with architecture 'x64' was not found for Windows 2022.
The list of all available versions can be found here: https://raw.githubusercontent.com/actions/python-versions/main/versions-manifest.json

I recommend also dropping 2.7.