Support --disable-gil builds (PEP 703) in packaging.tags

[colesbury]

This updates packaging.tags to compute the correct tags for the experimental CPython 3.13 --disable-gil builds.

Closes #727

[brettcannon]

I think we can be a bit more deliberate in flagging that a threaded build is occurring to make the _abi3_applies() check potentially less brittle (we have to assume old versions of this package will be used in old versions of pip on new versions of Python, so we're paranoid about this stuff 😅).

[brettcannon]

Since this is only internal code where attempts to fill in abi3 applies, I've decided to try not to stress about this. 😅

[pradyunsg]

Logistical question: Are we supposed to wait until PEP 703 is marked as accepted?

[brettcannon]

Logistical question: Are we supposed to wait until PEP 703 is marked as accepted?

It's essentially accepted and this technical detail won't change (I have proof-read the official acceptance announcement that's being drafted 😁).

[pradyunsg]

Let's do this then! 🎉

[hugovk]

PEP 703 has now been formally accepted 🚀

• https://peps.python.org/pep-0703/
• https://discuss.python.org/t/pep-703-making-the-global-interpreter-lock-optional-in-cpython-acceptance/37075

Please could we have a new packaging release with this?

It would unblock early work trying to build projects with --disable-gil:

        File "/private/var/folders/c8/hl_96fcs0hjgr29njx33x20c0000gn/T/pip-build-env-813wpsdv/normal/lib/python3.13/site-packages/wheel/bdist_wheel.py", line 356, in get_tag
          tag in supported_tags
      AssertionError: would build wheel with unsupported tag ('cp313', 'cp313td', 'macosx_13_0_arm64')

Thanks!