Bump python to version 3.13

[renatomello]

Can we bump the python version to 3.13? It was released last October and 3.13.1 was released in December. Right now qibo is capping the versions at 3.12, so it is creating installation issues.

[alecandido]

@renatomello there is already a PR since October, and a discussion is in there #1484.

The current problem is that bumping it would cause the CI to fail, since it depends on qiboml (i.e. since it is testing the TensorFlow and PyTorch backends), and TensorFlow does not support yet py3.13
https://pypi.org/project/tensorflow/2.18.0/#files

In any case, the correct solution would be to exclude the Qiboml backends from Qibo CI. But we need to test them anyhow, and we'd like to avoid duplicating all the backends test. That's perfectly possible, but we need to invest a bit more to decide how to test backends which our outside the qibo repository (including Qibojit, finally cutting the annoying PRs cycle...).

End of the story: it takes some time, and there is no person power available to speed up the process.

As soon as TensorFlow will support py3.13, we will immediately support it. Soon enough, we hope to lift this requirement (which we started doing by removing the TensorFlow backend from this repo in the first place, but we need a further step).

[renatomello]

OK, thanks. I'm closing this issue then.