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

Conflicts:
- app/models/media_attachment.rb
  Upstream added audio attachment support
- app/serializers/initial_state_serializer.rb
  Upstream added audio attachment support and how mimetypes are returned
- app/serializers/rest/instance_serializer.rb
  Upstream added a few fields
- config/application.rb
  Upstream added a different paperclip transcoder

app/javascript/mastodon/locales/ja.json

@@ -374,7 +374,7 @@
   "trends.count_by_accounts": "{count}人がトゥート",
   "ui.beforeunload": "Mastodonから離れると送信前の投稿は失われます。",
   "upload_area.title": "ドラッグ＆ドロップでアップロード",
-  "upload_button.label": "メディアを追加 (JPEG, PNG, GIF, WebM, MP4, MOV)",
+  "upload_button.label": "メディアを追加 ({formats})",
   "upload_error.limit": "アップロードできる上限を超えています。",
   "upload_error.poll": "アンケートではファイルをアップロードできません。",
   "upload_form.description": "視覚障害者のための説明",