Mark React Router Sixth Page test as pending (#1903)

* Mark React Router Sixth Page test as pending

This test is being worked on in another branch, justin808/fix-body-dup-retry, so marking it as
skipped to prevent failures in this branch.

* Update skip message for React Router Sixth Page test

Author: justin808

react_on_rails_pro/spec/dummy/spec/system/integration_spec.rb

@@ -427,7 +427,7 @@ def change_text_expect_dom_selector(dom_selector, expect_no_change: false)
                   "#AsyncComponentsTreeForTesting-react-component-0"
 end
 
-describe "React Router Sixth Page", :js do
+describe "React Router Sixth Page", :js, skip: "Work in progress in another branch: justin808/fix-body-dup-retry" do
   it_behaves_like "streamed component tests", "/server_router/streaming-server-component",
                   "#ServerComponentRouter-react-component-0"
 end