Merge pull request #200 from wazo-platform/WAZO-3118-run-pyupgrade

Run pyupgrade (py37) to update to a more modern syntax

pyupgrade was limited to py37 features as we need to remain compatible with Python 3.7 for plugins for now.
Annotations can be updated as they are lazy and not used at runtime.

Reviewed-by: Francois Blackburn <None>