Merge branch 'main' into glitch-soc/merge-upstream

Conflicts:
- `README.md`:
  Upstream updated copyright year, we don't mention it so kept our version.
- `app/controllers/admin/dashboard_controller.rb`:
  Not really a conflict, upstream change (removing the spam checker) too close
  to glitch-soc changes. Ported upstream changes.
- `app/models/form/admin_settings.rb`:
  Same.
- `app/services/remove_status_service.rb`:
  Same.
- `app/views/admin/settings/edit.html.haml`:
  Same.
- `config/settings.yml`:
  Same.
- `config/environments/production.rb`:
  Not a real conflict, upstream added a default HTTP header, but we have
  extra headers in glitch-soc.
  Added the header.

app/controllers/admin/dashboard_controller.rb

@@ -36,7 +36,6 @@ module Admin
       @profile_directory     = Setting.profile_directory
       @timeline_preview      = Setting.timeline_preview
       @keybase_integration   = Setting.enable_keybase
-      @spam_check_enabled    = Setting.spam_check_enabled
       @trends_enabled        = Setting.trends
     end