Merge branch 'feature/venue-admin' into 'develop'

src/backoffice/forms.py

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

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

src/backoffice/templates/backoffice/base.html

...ce/templates/backoffice/conferences/publication_edit.html

...e/templates/backoffice/conferences/registration_edit.html

...ackoffice/templates/backoffice/conferences/selection.html

src/backoffice/urls.py

src/backoffice/views/conferences.py

src/backoffice/views/misc.py

src/backoffice/views/mixins.py

src/core/fixtures/bootstrap_auth_groups.json

src/core/forms.py

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

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

src/core/migrations/0152_alter_conferencemember_options.py

src/core/migrations/0153_alter_conferencemember_options.py

src/core/models/conference.py