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/services/post_status_service.rb

@@ -107,7 +107,7 @@ class PostStatusService < BaseService
 
     @media = @account.media_attachments.where(status_id: nil).where(id: @options[:media_ids].take(4).map(&:to_i))
 
-    raise Mastodon::ValidationError, I18n.t('media_attachments.validations.images_and_video') if @media.size > 1 && @media.find(&:video?)
+    raise Mastodon::ValidationError, I18n.t('media_attachments.validations.images_and_video') if @media.size > 1 && @media.find(&:audio_or_video?)
   end
 
   def language_from_option(str)