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

Conflicts:
- `README.md`:
  Minor upstream change, our README is completely different.
  Kept ours.
- `lib/tasks/assets.rake`:
  glitch-soc has extra code to deal with its theming system,
  upstream changed a line that exists in glitch-soc.
  Applied upstream changes.

app/controllers/concerns/signature_verification.rb

@@ -227,7 +227,7 @@ module SignatureVerification
   end
 
   def to_header_name(name)
-    name.split(/-/).map(&:capitalize).join('-')
+    name.split('-').map(&:capitalize).join('-')
   end
 
   def missing_required_signature_parameters?