Use update_attribute in Rake task
Use update_attribute in Rake task

The `update` method performs validation, some editions are failing
validation (mostly archived ones where they're not allowed to be
edited). Although it shouldn't matter as only draft editions have an
`auth_bypass_id`, I would prefer that all editions have one so we can be
confident the value won't ever be `nil`.

alphagov/publisher,alphagov/publisher,alphagov/publisher