Fix reference to Application#configuration to use #config

railties/test/application/configuration_test.rb

@@ -60,7 +60,7 @@ def setup
       RUBY
 
       require "#{app_path}/config/application"
-      assert AppTemplate::Application.configuration.action_controller.allow_concurrency
+      assert AppTemplate::Application.config.action_controller.allow_concurrency
     end
 
     test "the application can be marked as threadsafe when there are no frameworks" do