Move SASS sources to the public directory to make the style.css accessible without a titofisto token

Update poetry.lock

See merge request !746

Resolve "[2FA] Login form requires otp multiple times"

Closes #507

See merge request !743

Update changelog from 2.0rc7

See merge request !744

(cherry picked from commit daa42d42)

Resolve "Revert "Support custom authentication backends" wasn't done cleanly"

Closes #521

See merge request !741

Resolve "Fix Brand logo on mobile devices"

Closes #520

See merge request !739

Add missing changelog entry

See merge request !738

Resolve "KeyError: 'SCOPES'  with OAUTH2_PROVIDER"

Closes #518

See merge request !736

Resolve "django-sass-processor searches style.css in wrong storage"

Closes #519

See merge request AlekSIS/official/AlekSIS-Core!737

Update changelog from 2.0rc6

See merge request !735

(cherry picked from commit e7f647bf)
(cherry picked from commit 3b3ed902)
(cherry picked from commit ca6481d1)
(cherry picked from commit 501a1d6a)

Fix dependency django-phonenumber-field

See merge request !734

Fix and cleanup changelog

See merge request !732

Make admin from/contact settings default to initial superuser

See merge request !727

Resolve "Deleting persons is impossible"

Closes #487

See merge request !728

Set version for django-dynamic-preferences to ^1.11 to include fix which makes deleting persons possible again

Resolve "ALLOWED_HOSTS violations are too loud"

Closes #517

See merge request !731