After merge "Bump paperclip from 5.2.1 to 6.1.0 #3905" as indicated in
the release_notes columns type for attachments are changed from integer
to bigint.
For this reason we edit old migrations so that they continue to
generate integer as before.
DEPRECATION WARNING: Directly inheriting from ActiveRecord::Migration
is deprecated. Please specify the Rails release the migration was
written for:
class MigrationClass < ActiveRecord::Migration[4.2]
(called from require at bin/rails:4)