Add Python 3.11, drop Python 3.7

[eumiro]

No description provided.

[klieret]

Thanks for opening the PR! Much appreciated :) Do you have any idea why the windows check is failing? (assuming it was not just a fluke)

[eumiro]

I tried to relaunch it on my branch, always with the same error. I'd maybe try to rewrite the tests using pytest syntax with the tmp_path fixture and leave all files in the directory.