Does not support pytest >= 8.5.0

[ayakael]

Pytest 8.5.0 introduced two changes that breaks pytest-unmagic:

• Remove _pytest.compat.is_generator() fixes #12960 pytest-dev/pytest#12968
• (fixtures): Replace fixture represenation with a class pytest-dev/pytest#12473

[millerdev]

Looks like it's actually 8.4+ that's not supported. Hopefully will have a fix out soon.