👷🏼🐍 Enable testing on Python 3.15

[denialhaag]

🤖 AI text below 🤖

We cannot enable testing on Python 3.15 yet, since we first have to wait for our dependencies to provide 3.15 wheels. This issue tracks the work so we don't forget once they are available.

Once ready, "3.15" has to be added to PYTHON_ALL_VERSIONS in noxfile.py:

qcec/noxfile.py

Line 35 in 3d20a3e

PYTHON_ALL_VERSIONS = ["3.11", "3.12", "3.13", "3.14"]

Furthermore, the cp315* test skip has to be removed in pyproject.toml:

qcec/pyproject.toml

Line 312 in 3d20a3e

select = ["cp*-win_arm64", "cp315*"]