Removed add_index from AddExpiresAtToStatus

• Removed:
- add_index from AddExpiresAtToStatus

db/migrate/20200722190844_add_expires_at_to_status.rb

@@ -1,6 +1,5 @@
 class AddExpiresAtToStatus < ActiveRecord::Migration[5.2]
   def change
     add_column :statuses, :expires_at, :datetime
-    add_index :statuses, :expires_at
   end
 end