Update supported Python versions (3.13, even 3.14?, remove 3.8?)

[paugier]

At least, 3.13 should be added in the CI.

I guess a new version should be released with wheels for the supported Python versions.

Note that there are currently no wheels for 3.12 (https://pypi.org/project/hpy/#files).

[hodgestar]

Agreed. We could even remove 3.9, perhaps.