Merge branch '404-remove-old-data-check-results-if-the-data-problem-persists-no-longer' into 'master'

Resolve "Remove old data check results if the data problem persists no longer"

Closes #404

See merge request !580

Enable the Django REST framework

See merge request !586

Resolve "Serve as OAuth2 and OpenID Connect provider"

Closes #235

See merge request !415

Merge branch '235-serve-as-saml-and-oauth2-provider' of edugit.org:AlekSIS/official/AlekSIS-Core into 235-serve-as-saml-and-oauth2-provider

Resolve "Replace/remove django-middleware-global-request"

Closes #193

See merge request !584

Resolve "Allow using Django-local accounts in addition to LDAP accounts"

Closes #388 und #389

See merge request !501

Add missing migration for PDFFile

See merge request !576

Update dependency importlib-metadata to v4

See merge request !577

Resolve "Remove title from dashboard"

Closes #428

See merge request !581

Resolve "Fix link of header brand logo text"

Closes #427

See merge request !582

Resolve "Allow control over self-editing of person"

Closes #245

See merge request !563

Update dependency django-any-js to ^1.1

See merge request !579

Support storage location for s3

See merge request !578

Update copyright information for 2021 (and partially for 2020)

See merge request !575

Merge branch '357-support-pdf-generation-via-electron-pdf-running-in-the-background-using-celery' into 'master'

Resolve "Support PDF generation via a headless Chromium running in the background using celery"

Closes #357

See merge request !464