Skip "action mailer missing" example for Rails 7

See rails/rails#43508

Author: pirj

example_app_generator/spec/verify_mailer_preview_path_spec.rb

@@ -111,6 +111,8 @@ def have_no_preview
       end
 
       it 'handles action mailer not being available' do
+        skip "Rails 7 forces eager loading on CI, loads app/mailers and fails" if Rails::VERSION::STRING.to_f >= 7.0
+
         expect(
           capture_exec(
             custom_env.merge('NO_ACTION_MAILER' => 'true'),