[MNT] python 3.13 compatibility

[fkiraly]

We should test 3.13 compatibility on the release candidate rc3, and prepare for the release on 3.13 on Oct 7.

I foresee no compatibility issues as long as the dependencies keep up with 3.13.

The main issue may be numpy, of which we still require version 1, see #1624 - any chance we can resolve this, @XinyuWuu?

Perhaps just not supporting numpy 2 on mac x86?

[fkiraly]

The numpy 2 issue is resolved by moving to macos-latest.

[XinyuWuu]

Perhaps just not supporting numpy 2 on mac x86?

It's the only solution I think. If users wants numpy2 and torch on mac x86, they can try to compile torch locally but it's guaranteed by pytorch.