Attributes don't play nicely with ActiveModel::Dirty in Rails 6

[edtjones]

We've hit a problem on a project where the functionality of ActiveModel::Dirty has changed, such that the following no longer works for a Her-backed model:

foo = SomeModel.find(1)
foo.title # returns a string
foo.title = 'bar'
foo.restore_title! #should restore the title; actually fails because foo.title is a String and Rails 6 expects it to respond to `original_value`.

Haven't done enough digging to determine the best course of action for fixing, yet.