WHL: build and test wheels against CPython 3.14 (GIL-enabled) (twin #18457) - #18458

Thank you for your contribution to Astropy! 🌌 This checklist is meant to remind the package maintainers who will review this pull request of some common things to look for.

• Do the proposed changes actually accomplish desired goals?
• Do the proposed changes follow the Astropy coding guidelines?
• Are tests added/updated as required? If so, do they follow the Astropy testing guidelines?
• Are docs added/updated as required? If so, do they follow the Astropy documentation guidelines?
• Is rebase and/or squash necessary? If so, please provide the author with appropriate instructions. Also see instructions for rebase and squash.
• Did the CI pass? If no, are the failures related? If you need to run daily and weekly cron jobs as part of the PR, please apply the "Extra CI" label. Codestyle issues can be fixed by the bot.
• Is a change log needed? If yes, did the change log check pass? If no, add the "no-changelog-entry-needed" label. If this is a manual backport, use the "skip-changelog-checks" label unless special changelog handling is necessary.
• Is this a big PR that makes a "What's new?" entry worthwhile and if so, is (1) a "what's new" entry included in this PR and (2) the "whatsnew-needed" label applied?
• At the time of adding the milestone, if the milestone set requires a backport to release branch(es), apply the appropriate "backport-X.Y.x" label(s) before merge.

👋 Thank you for your draft pull request! Do you know that you can use [ci skip] or [skip ci] in your commit messages to skip running continuous integration tests until you are ready?

Interesting, there are failures on some platform, but not all, while nothing fails on main (though admittedly main has a different set of wheels, using abi3 targets). I'll inspect this in more details tomorrow.

Do we really need GIL-enabled Python 3.14 build in v7.1.x?

I don't know, but it seems worth exploring. I'd like whatever our next release is to have 3.14-compatible wheels, and if we can't do that, at least learn why.

v7.2 (or v8.0, depending on how the astropy-dev discussions go) would be out by the end of 2025 (a few months) and then we don't have to worry about v7.1.x anymore, right? If it comes "for free," sure, but red CI here suggests otherwise.

Actually it seems to me that the one failure we're seeing shows that #18139 wasn't actually included in 7.1.0 (as the milestone would suggest), but since it's a bug fix, we might as well just backport it now. I'll try this here to confirm that the approach is sound, and if so, I'll give it its own backport PR.

Looking good, here's the dedicated backport #18461

I don't understand. The backport PR (#18156) was merged.

oh, weird. The auto-backported only included 1 in 3 commits. My manual backport has the other 2.