Prevent zeitwerk check from erroring on 6.1

Author: JonRowe

example_app_generator/no_active_record/config/initializers/zeitwerk.rb

@@ -1,3 +1,3 @@
-if Rails.autoloaders.respond_to?(:main)
+if Rails.autoloaders.respond_to?(:main) && Rails.autoloaders.main.respond_to?(:ignore)
   Rails.autoloaders.main.ignore('lib/rails/generators/in_memory/model/model_generator.rb')
 end