Fix setting action_dispatch.show_exceptions for Rails 7.2

Since Rails 7.1 we need to set this to `:none`.
The fix made was not very future proof...

spec/dummy/config/environments/test.rb

@@ -33,7 +33,7 @@
   config.cache_store = :null_store
 
   # Raise exceptions instead of rendering exception templates.
-  config.action_dispatch.show_exceptions = ENV.fetch("RAILS_VERSION", "7.1") == "7.1" ? :none : false
+  config.action_dispatch.show_exceptions = Rails.gem_version >= Gem::Version.new("7.1") ? :none : false
 
   # Disable request forgery protection in test environment.
   config.action_controller.allow_forgery_protection = true