Fix RenderingTest in railtie

Test class name is not `RoutingTest` but `RenderingTest`

railties/test/application/rendering_test.rb

@@ -4,7 +4,7 @@
 require "rack/test"
 
 module ApplicationTests
-  class RoutingTest < ActiveSupport::TestCase
+  class RenderingTest < ActiveSupport::TestCase
     include ActiveSupport::Testing::Isolation
     include Rack::Test::Methods