Sphinx 4.1 fixes

[flying-sheep]

This should do the trick.

Closes #35

[ivirshup]

• Have you checked if the scanpy docs build using this PR? (This might be a good CI check)
• How do we go about making a release after this, as the last fix didn't get merged?

[flying-sheep]

Good question. We could add the feature to get_version in which it only returns a VCS version if the git root matches, but idk if that would fix it or just throw a different error because now it can’t find any version.

[flying-sheep]

OK, I updated get_version. We don’t have to make another hacky hardcode release here