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.

lib/tasks/assets.rake

@@ -14,7 +14,7 @@ namespace :assets do
       File.write(dest, html)
     end
 
-    render_static_page 'errors/500', layout: 'error', dest: Rails.root.join('public', 'assets', '500.html')
+    render_static_page 'errors/500', layout: 'error', dest: Rails.public_path.join('assets', '500.html')
   end
 end