tests(ci): Fix python version with poetry caching and actions/setup-python@v3
tests(ci): Fix python version with poetry caching and actions/setup-python@v3

poetry install will pick up the python binary at the time it was
installed (before actions/python ran) so it looks like poetry env needs
to be set manually.

https://github.com/actions/setup-python/releases/tag/v3.1.0
https://github.com/actions/setup-python/tree/v3.1.0
https://github.com/actions/setup-python/pull/281

tony/libvcs