Stable ABI filename new form in Python 3.15+

[henryiii]

In 3.15+, foo.abi3-x86-64-linux-gnu.so will become a valid name (alongside the existing foo.abi3.so), see python/cpython#152461. I believe some combination of meson-python (validation in _WheelBuilder._stable_abi) and probably meson (to be able to generate them) need to be updated to handle this.

[rgommers]

Thanks @henryiii! meson should already do the right thing, assuming that abi3-x86-64-linux-gnu landed ahead of abi3 in the priority order. In meson-python I'd expect we have to update tests at a minimum, and probably also the checks for all extensions being abi3 yes or no.