CPython 3.13 support (tracker issue)

[neutrinoceros]

This issue is to plan and keep track on the effort to add support for CPython 3.13 . See PEP 719 for the release schedule. At the time of opening, version 3.13.0b2 is available, and NumPy is already publishing nightly wheels for it.

Here's the chronological task list to complete before we can declare support for it.

• [x] wait for our core dependencies to publish nightly builds, or be tested
  • [x] numpy
  • [x] matplotlib https://github.com/matplotlib/matplotlib/pull/28293
    • [x] Pillow
    • [x] contourpy
  • [ ] unyt https://github.com/yt-project/unyt/pull/507 (not a real requirement: unyt 3.0.3 appear to be compatible already)
  • [x] cmyt https://github.com/yt-project/cmyt/pull/178
  • [x] ewah-bool-utils https://github.com/yt-project/ewah_bool_utils/pull/108
• [ ] https://github.com/yt-project/yt/pull/4958
• [x] pass all tests on ubuntu
• [ ] test cp313 wheels builds for all platform in CI (but don't publish them yet)
  • [x] this is helped by #4949
  • [x] ... and #4971
  • [ ] #4973
• [ ] enable publication to PyPI
  • [x] requires ABI stability, i.e., CPython 3.13.0rc1
  • [ ] #4973

Supporting the experimental free-threading (a.k.a "nogil") build is a non-goal for this issue. Relevant PRs are to be linked in this message.