Switch to a maintained alternative for pyscss

The following discussion from !226 (closed) should be addressed:

• @gk started a discussion: (+2 comments)

  @gk: I have updated the dependency for pyscss to use the latest main branch of it's github repository as the project seems to be abandoned, and the latest commit which fixes the compatibility with Python 3.11 doesn't seem to have been released as a new tag.

  Okay, thanks! Relying on unmaintained code makes me a bit itchy. Is there a maintained package that provides the same functionality which we might be able to switch to?