Currently `delete` is used on the `purge` and `purge_later` methods,
that prevent any callbacks to be triggered which causes the parent
model to not be updated when an attachment is purged. This behaviour
cause issues on some caching strategies as reported here: https://github.com/rails/rails/issues/39858

Changes:

* Add `record&.touch` on `attachment#purge`
* Add `record&.touch` on `attachment#purge_later`
* Remove extra blank line on attachment.rb
* Add tests which are failing before this change and pass after the change