Implement support for PEP 793

[ngoldbaum]

See https://peps.python.org/pep-0793/ for more details.

It's likely this will be a pre-requisite for supporting the new version of the stable ABI for Python 3.15.

[davidhewitt]

Do we need to wait for 3.15 to mature before investing effort in this?

[ngoldbaum]

I think it'll make sense to work on this once PEP 803 or PEP 809 are accepted and there's a new stable ABI to use on 3.15. That will require quite a bit of work and we'll need to get the ecosystem ready for shipping wheels with the new ABI, so IMO the sooner starting on that the better.

[encukou]

The PEP 793 feature (and the API surface) might still change in CPython alphas & betas, but I hope the mechanism is here to stay.