Fix stack level too deep error

Further information can be found in the Github issue.
solidusio/solidus#6326

Author: AlistairNorman

Gemfile

@@ -20,6 +20,8 @@ end
 rails_requirement_string = ENV.fetch("RAILS_VERSION", "~> 8.0")
 gem "rails", rails_requirement_string
 
+gem 'state_machines', '0.6.0'
+
 # Provides basic authentication functionality for testing parts of your engine
 gem "solidus_auth_devise"