CI: Various minor improvements to fix CI

[bsipocz]

This should work around one of the CI issues. I can't yet reproduce the other one locally.

fixes #185

[bsipocz]

I suppose looking at other PRs would have been a quicker way to figure out the mpl version changes, nevertheless, I feel the addition of some verbosity for the versions is still useful, so I left all the debug commits in there.

Also, this now includes the cherry-picked commit from #183 as a way to trigger CI for that one.

[bsipocz]

cc @fangohr - this is ready to go. Let me know if any of the changes are controversial and if you prefer them to be removed.

[fangohr]

This looks great @bsipocz, thank you for that contribution! I like the additional pip freeze debug info, moving to python 3.10, and sanitising the figure size.

Thank you @bnavigator for the sanitizing figure contribution in #183 !

I left one minor query in the code changes.