Replace SCSS compilation with CSS variables (#4191)

* Replace SCSS compilation with CSS variables

* Update tests

* Update src/pretix/presale/style.py

Co-authored-by: Mira <weller@rami.io>

* Update src/pretix/presale/context.py

Co-authored-by: Mira <weller@rami.io>

* Update src/pretix/presale/views/widget.py

Co-authored-by: Mira <weller@rami.io>

* Update src/pretix/presale/context.py

Co-authored-by: Mira <weller@rami.io>

* Update src/pretix/static/pretixbase/scss/_variables.scss

Co-authored-by: Richard Schreiber <schreiber@rami.io>

* Last minor changes

* Rename file

---------

Co-authored-by: Mira <weller@rami.io>
Co-authored-by: Richard Schreiber <schreiber@rami.io>

src/pretix/api/views/event.py

@@ -57,10 +57,8 @@ from pretix.base.models import (
 )
 from pretix.base.models.event import SubEvent
 from pretix.base.services.quotas import QuotaAvailability
-from pretix.base.settings import SETTINGS_AFFECTING_CSS
 from pretix.helpers.dicts import merge_dicts
 from pretix.helpers.i18n import i18ncomp
-from pretix.presale.style import regenerate_css
 from pretix.presale.views.organizer import filter_qs_by_attr
 
 with scopes_disabled():
@@ -636,8 +634,6 @@ class EventSettingsView(views.APIView):
                         k: v for k, v in s.validated_data.items()
                     }
                 )
-        if any(p in s.changed_data for p in SETTINGS_AFFECTING_CSS):
-            regenerate_css.apply_async(args=(request.event.pk,))
         s = EventSettingsSerializer(
             instance=request.event.settings, event=request.event, context={
                 'request': request