Fix a regression introduced in rails/rails@4b1122c with the upgrade to Rails 6.1.4.1. Triggered by a call to `SELECT * FROM ip_geolocations WHERE ip_addr in ...`. A Rails refactoring changed the way that `WHERE ... IN ...` statements worked, which had the side effect of passing a string value to our IpAddressType serializer where before we expected a Danbooru::IpAddress object.