devel/py-cookiecutter: switch to USE_PYTHON=pytest

Use the standard pytest setup. Disable one windows specific test

While here, allow py311 flavor. Upstream has not specified 3.11 as
supported, but there hasn't been any significant development on this
module since before python-3.11 was released, and the code runs just
fine. This means that a py311 flavour of molecule should now be
available.

No portrevision bump, as this just adds a new flavour; existing
flavours are unchanged.