Rename encrypted_attributes to attr_encrypted_attributes

[r7kamura]

Because activerecord 7 has a method with the same name.

• https://github.com/rails/rails/blob/v7.0.2.3/activerecord/lib/active_record/encryption/encryptable_record.rb#L11

This change fixes some errors like this:

• attr_encrypted is incompatible with the upcoming Rails 7 ActiveRecord::Encryption API devise-two-factor/devise-two-factor#192

[chadwilken]

Any chance on getting this fixed up and merged? I imagine this has to be blocking quite a few people on a Rails 7 upgrade.

[joshbranham]

Fixed in #434 to be released via #435