Autofix Rubocop Style/BlockDelimiters (#23706)

db/migrate/20171020084748_add_visible_in_picker_to_custom_emoji.rb

@@ -1,7 +1,7 @@
 class AddVisibleInPickerToCustomEmoji < ActiveRecord::Migration[5.1]
   def change
-    safety_assured {
+    safety_assured do
       add_column :custom_emojis, :visible_in_picker, :boolean, default: true, null: false
-    }
+    end
   end
 end