Merge branch 'fix/assembly-managers' into 'develop'

src/backoffice/forms/assemblies.py

src/backoffice/locale/de/LC_MESSAGES/django.po

src/backoffice/locale/en/LC_MESSAGES/django.po

src/backoffice/views/assemblies/members.py

src/core/exceptions.py

src/core/locale/de/LC_MESSAGES/django.po

src/core/locale/en/LC_MESSAGES/django.po

src/core/models/assemblies.py

src/core/models/teams/team_member.py