reorganize debian dependencies
reorganize debian dependencies

* Use consistent formatting for Depends section.
* Move python dependencies to grouprise binary
  package as the grouprise-dependencies package
  only contains additional venv dependencies.
* Separate grouprise python dependencies in the
  Build-Depends section of the source package so
  that it is more clear which dependencies have
  been added because the grouprise application
  rather than the build process depend on them.

stadtgestalten/stadtgestalten,stadtgestalten/stadtgestalten,stadtgestalten/stadtgestalten