[Docs] Data checks

See merge request AlekSIS/official/AlekSIS-Core!926

[Docs] Registration and user invitations

See merge request !922

Resolve "'FieldInstanceTracker' object has no attribute 'saved_data'"

Closes #639

See merge request AlekSIS/official/AlekSIS-Core!948

Resolve "Migration 0035_preference_model_unique still broken"

Closes #638

See merge request AlekSIS/official/AlekSIS-Core!949

django-model-utils' documentation states that using the relation is not stable in all situations.

Bump version to 2.7.2 and update changelog

See merge request !946

Translations update from Weblate

See merge request !930

Currently translated at 99.8% (645 of 646 strings)

Translation: AlekSIS/AlekSIS-Core
Translate-URL: https://translate.edugit.org/projects/aleksis/aleksis-core/de/

Update translation files

See merge request !945

Use separate database connection for Celery results

See merge request !943

This ensures Celery progress is always updated and queried outside a
transaction.

[Docker] Clear caches on migrate

See merge request !944

Rename PDF_CONTEXT_PROCESSORS

See merge request !942

Prepare release 2.7.1

See merge request !940

Resolve "get() returned more than one PersonPreferenceModel [Ticket#75959]"

Closes #633

See merge request !937

Merge remote-tracking branch 'origin/master' into 633-get-returned-more-than-one-personpreferencemodel-ticket-75959

More default schedules

See merge request !939