[Backport to 2.0] Use importlib instead of pkg_resources to discover dist

Backport of !642 (merged)

Please test:

• About page, specifically display of versions

added type::bug label

changed title from [Backport to 2.0] [Docs] Add missing proxy upstream to nginx config to [Backport to 2.0] Use importlib instead of pkg_resources to discover dist

Backports will be done en bloc.

closed