Cast samples to int32 - Githubissues

Attempt to fix #1412. In principle we could replace the default dtype in backends to something more useful (e.g. type(x)) however this is not trivial because this function was designed for state vectors. PS. I prefer to dtype=np.uint8 however torch does not like it.

Checklist:

[ ] Reviewers confirm new code works as expected.
[ ] Tests are passing.
[ ] Coverage does not decrease.
[ ] Documentation is updated.

qiboteam / qibo

Cast samples to int32 #1415