Add Python 3.14 (tests, docs, configuration)

[niccokunzmann]

Python 3.14 is released.

Please update all files to auto test this version in documentation, CI, tests.

[AnandRaj2224]

Hi @niccokunzmann , I'd like to try working on this issue. Could you please assign it to me?

[niccokunzmann]

@AnandRaj2224 Thank you! No assignment is needed. Just start working on it and open a pull request as soon as possible.