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

Conflicts:
- `.github/dependabot.yml`:
  Updated upstream, we deleted it to not be flooded by Depandabot.
  Kept deleted.
- `Gemfile.lock`:
  Puma updated on both sides, went for the most recent version.
- `app/controllers/api/v1/mutes_controller.rb`:
  Upstream updated the serializer to support timed mutes, while
  glitch-soc added a custom API ages ago to get information that
  is already available elsewhere.
  Dropped the glitch-soc-specific API, went with upstream changes.
- `app/javascript/core/admin.js`:
  Conflict due to changing how assets are loaded. Went with upstream.
- `app/javascript/packs/public.js`:
  Conflict due to changing how assets are loaded. Went with upstream.
- `app/models/mute.rb`:
  🤷
- `app/models/user.rb`:
  New user setting added upstream while we have glitch-soc-specific
  user settings. Added upstream's user setting.
- `config/settings.yml`:
  Upstream added a new user setting close to a user setting we had
  changed the defaults for. Added the new upstream setting.
- `package.json`:
  Upstream dependency updated “too close” to a glitch-soc-specific
  dependency. No real conflict. Updated the dependency.

app/lib/activitypub/activity.rb

@@ -74,7 +74,7 @@ class ActivityPub::Activity
     @object_uri ||= begin
       str = value_or_id(@object)
 
-      if str.start_with?('bear:')
+      if str&.start_with?('bear:')
         Addressable::URI.parse(str).query_values['u']
       else
         str

app/lib/activitypub/tag_manager.rb

@@ -40,6 +40,10 @@ class ActivityPub::TagManager
     end
   end
 
+  def uri_for_username(username)
+    account_url(username: username)
+  end
+
   def generate_uri_for(_target)
     URI.join(root_url, 'payloads', SecureRandom.uuid)
   end