Avoid problematic versions of state_machines

Due to an issue with state machines, we get a stack level too deep error
when using newer versions of state machines.

Author: AlistairNorman

Gemfile

@@ -4,6 +4,11 @@ source 'https://rubygems.org'
 
 gem 'rails', ENV['RAILS_VERSION'] || '~> 7.2.0'
 
+branch = ENV.fetch("SOLIDUS_BRANCH", "main")
+if branch <= "v4.5" || branch == "main"
+  gem "state_machines", "<= 0.6"
+end
+
 group :development do
   gem 'guard'
   gem 'guard-shell'