Update Python versions in the CI workflow.

[ezio-melotti]

This PR updates the Python versions in the CI workflow.

[ezio-melotti]

Looks like it worked! I was looking at https://github.com/actions/setup-python/blob/main/docs/advanced-usage.md#available-versions-of-python-and-pypy and didn't see 3.12, so I just went with the safest option.

I was also considering keeping 3.11-dev because IIUC it will test e.g. 3.11.1a0 and following releases instead of waiting for 3.11.1 final. What do you think?

[hugovk]

Looks like it worked! I was looking at https://github.com/actions/setup-python/blob/main/docs/advanced-usage.md#available-versions-of-python-and-pypy and didn't see 3.12, so I just went with the safest option.

Yep, that links to the full list at https://raw.githubusercontent.com/actions/python-versions/main/versions-manifest.json which has 3.12a0 - 3.12a2, and 3.12-dev maps onto the latest available.

I was also considering keeping 3.11-dev because IIUC it will test e.g. 3.11.1a0 and following releases instead of waiting for 3.11.1 final. What do you think?

GitHub's -dev follows the latest CPython releases, alpha, beta, RC, full. And there aren't 3.11.1a0 releases, just 3.11.1, 3.11.2 etc.

(Travis CI's -dev releases are different, they're nightly builds. If we ever want to test the cutting edge on GHA we can use https://github.com/deadsnakes/action)