ENH: Multiple CI changes

[cookpa]

• Main one is a new script to quickly test python-only changes using cached wheels

• Duplicate wheels.yml because I can't figure out how to set matrix dynamically, and build a subset of wheels on push to master

• Set main wheels.yml to build the full matrix nightly, or upon release creation

Fixes #567

[cookpa]

New testing script: The fast test will take an hour or so the first time, because it builds and caches antspyx from source. But subsequent runs should take only about 5 minutes, as long as only the python code changes. Any changes to setup.py, requirements.txt, or anything in lib/ will trigger a cache miss. If there's no activity after seven days, the cache expires.

Changes to wheels.yml:

• Change pypi steps to only run on release, rather than on push. This avoids duplication when a release is created after a tag is pushed

• don't run on every PR or push, but run nightly

  Reduced set of wheels just builds Python 3.9 (3.10 on ARM64). This happens on push to master, and is an intermediate level of checking. I chose python 3.9 rather than 3.12 because I figure we're probably mostly using newer Python on our own development machines, and we're probably more likely to introduce new code that isn't backwards compatible, than to use deprecated functions that aren't forward compatible.

  At some point there might be compelling reason to break backwards compatibility, at which point we can update all the tests and remove the old versions from the release matrix.

  Feedback welcome. I'd be happy to build the full set of wheels wheels weekly rather than nightly, if that's OK with everyone. I think most users are downloading from PyPI anyway