Support Python 3.11

[jklaise]

Python 3.11 came out on 27/10/22 so we should look to support it soon. However, as always, we're mainly limited by upstream support from tensorflow and torch:

• Support Python 3.11 tensorflow/tensorflow#58032 (PR included in tf 2.12).
• Support Python 3.11 pytorch/pytorch#86566 (3.11 support, not including torch.compile, included in torch 2.0).
• Python 3.11 numba/numba#8304 (PR merged, will be included in 0.57.0 according to this).

[ascillitoe]

Added numba to the list.

This might actually be our main blocker since torch and tensorflow are optional now?

[jklaise]

@ascillitoe good point, however, I think we should wait before both tensorflow and torch are Python 3.11 compatible to claim that both our libraries are too given how extensively we use those two (also CI would fail since we install both by default to test everything).

[ascillitoe]

Ah yeh good point about CI!