BUG: adapt to platform-specific abi3 and abi3t filename suffixes

[dnicolodi]

Python 3.15.0rc1 introduced platform-specific filename suffixes for stable ABI extension modules alongside the generic ".abi3" and ".abi3t".

[rgommers]

Thanks @dnicolodi! It looks like we lost CI coverage for free-threading with the demise of Cirrus. I tried adding 3.15t jobs for Linux and Windows; Linux is happy, but Windows shows two test failures: https://github.com/rgommers/meson-python/actions/runs/31088854382/job/92574711478.

The changes to _WheelBuilder look too strict, we need to be careful there until we land a cross-compilation CI job.

[dnicolodi]

Windows shows two test failures

I see why this fails. The fact that stable ABI extension modules do not have a dedicated filename suffix on Windows is a pain.

[rgommers]

The fact that stable ABI extension modules do not have a dedicated filename suffix on Windows is a pain.

💯. Doesn't seem like there's any interest upstream in fixing that, unfortunately. Maybe once they finally replace their build systems with something more modern.

[eli-schwartz]

The fact that stable ABI extension modules do not have a dedicated filename suffix on Windows is a pain.

💯. Doesn't seem like there's any interest upstream in fixing that, unfortunately. Maybe once they finally replace their build systems with something more modern.

This was previously discussed around #787 (comment) and @zooba basically said it would be easy to do but nobody thought of it "because the original motivation for adding any kind of data there, was for a Linux specific reason and nobody really reevaluated the assumption since then".

[dnicolodi]

@rgommers I think I addressed your comments. Please take a look.

[dnicolodi]

@rgommers Unless you have more comments, I'll be merging this soon

[rgommers]

Thanks @dnicolodi! I had an event the week before last, so I had a hard time keeping up with OSS responsibilities. I did some post-hoc review here, this looks great now. I opened gh-882 as a follow-up with a couple of test improvements.

[dnicolodi]

Thanks @rgommers. I didn't want to force matters but I think it would be nice to have a release out soon to allow abi3t build of projects using meson-python, thus when I didn't hear from you for a while I went ahead as I felt that this was ready.

[rgommers]

Yeah no worries - you did ping me and announced your intention to merge, so all good. I was just so busy I didn't even read the ping in time (which is rare, luckily).

Also agreed that we need to get a release out. Let's try to do that this week?