Merge commit 'e0648a916ab81925545504173bf4f43ec64d4f3c' into glitch-soc/merge-upstream

Conflicts:
- `app/models/custom_emoji.rb`:
  An upstream refactor touched lines adjacent to ones modified in glitch-soc.
  Ported upstream's changes.

app/serializers/rest/instance_serializer.rb

@@ -109,9 +109,7 @@ class REST::InstanceSerializer < ActiveModel::Serializer
   end
 
   def api_versions
-    {
-      mastodon: 1,
-    }
+    Mastodon::Version.api_versions
   end
 
   private