Revert "Merge branch '186-sphinx-v3-0-incompatible-to-breathe-plugin' into 'master'"

What does this MR do?

Remove the version restriction on the Sphinx Python package. The Breathe plugin was updated and its latest version now only works with Sphinx >3.0

Is there something that needs to be double checked?

No

Can this MR be accepted?

• Pipeline passing
• Squash option set
• Delete branch option set
• Added entry to CHANGELOG.md

Assignee: If the Squash option is set, check/update the commit message right before merging!

Related issues

This reverts merge request !195 (merged)

This was resolved in Utopia by https://ts-gitlab.iup.uni-heidelberg.de/utopia/utopia/-/merge_requests/129