Autocorrect safe cops

One rule was disabled since we don't want to alter already performed
migrations.

app/controllers/commontator/comments_controller.rb

@@ -156,7 +156,7 @@ def upvote
 
     # PUT /comments/1/downvote
     def downvote
-      security_transgression_unless(@comment.can_be_voted_on_by?(@commontator_user) && \
+      security_transgression_unless(@comment.can_be_voted_on_by?(@commontator_user) &&
                                     @comment.thread.config.comment_voting.to_sym == :ld)
 
       @comment.downvote_from(@commontator_user)

app/helpers/media_helper.rb

@@ -147,6 +147,6 @@ def edit_or_show_medium_path(medium)
   def external_link_description_not_empty(medium)
     # Uses link display name if not empty, otherwise falls back to the
     # link url itself.
-    (medium.external_link_description.presence || medium.external_reference_link)
+    medium.external_link_description.presence || medium.external_reference_link
   end
 end

app/models/referral.rb

@@ -33,7 +33,7 @@ def vtt_time_span
 
   # provide metadata for vtt file
   def vtt_properties
-    link = (item.link.presence || item.medium_link)
+    link = item.link.presence || item.medium_link
     # at the moment, relations between items can be only of the form
     # script <-> video, which means that between them there will be at most
     # one script, one manuscript and one video

db/migrate/20201002094500_change_submission_foreign_keys.rb

@@ -1,4 +1,5 @@
 # rubocop:disable Rails/
+# rubocop:disable Lint/SymbolConversion
 class ChangeSubmissionForeignKeys < ActiveRecord::Migration[6.0]
   def up
     remove_index :user_submission_joins,
@@ -33,3 +34,4 @@ def id_to_uuid(table_name, relation_name, relation_class)
   end
 end
 # rubocop:enable Rails/
+# rubocop:enable Lint/SymbolConversion