Use selector to detect authenticity token input

Rails 7.0 adds the autocomplete attribute to hidden fields. By
switching to a selector, we can test both Rails 6 and 7

Author: tagliala

spec/rails/integration/forms_spec.rb

@@ -23,7 +23,7 @@
     end
 
     it "should include the hidden authenticity token" do
-      expect(html).to include '<input type="hidden" name="authenticity_token" value="AUTH_TOKEN" />'
+      expect(html).to have_selector('input[type="hidden"][name="authenticity_token"][value="AUTH_TOKEN"]', visible: :hidden)
     end
 
     it "should create a label" do