Merge commit 'c645490d553124d800d30488595f7d2d9d61584d' into glitch-soc/merge-upstream

Conflicts:
- `Gemfile.lock`:
  Changes were already cherry-picked and updated further in glitch-soc.
  Kept glitch-soc's version.
- `README.md`:
  Upstream updated its README, we have a completely different one.
  Kept glitch-soc's README.
- `app/models/account.rb`:
  Not a real conflict, upstream updated some lines textually adjacent
  to glitch-soc-specific lines.
  Ported upstream's changes.

app/javascript/mastodon/features/compose/components/upload_button.jsx

@@ -65,6 +65,7 @@ class UploadButton extends ImmutablePureComponent {
             key={resetFileKey}
             ref={this.setRef}
             type='file'
+            name='file-upload-input'
             multiple
             accept={acceptContentTypes.toArray().join(',')}
             onChange={this.handleChange}