old_contents: import json
  
  
  def test_govuk_frontend_jinja_overrides_on_design_system_v3():
      with open("package.json") as package_file:
          package_json = json.load(package_file)
  
      assert package_json["dependencies"]["govuk-frontend"].startswith("3."), (
          "After upgrading the Design System, manually validate that "
          "`app/templates/govuk_frontend_jinja_overrides/templates/components/*/template.njk`"
          "are all structurally-correct and up-to-date macros. If not, update the macros or retire them and update the "
          "rendering process."
      )
  
new_contents: import json
  
  
  def test_govuk_frontend_jinja_overrides_on_design_system_v3():
      with open("package.json") as package_file:
          package_json = json.load(package_file)
  
      assert package_json["dependencies"]["govuk-frontend"].startswith("3."), (
          "After upgrading the Design System, manually validate that "
          "`app/templates/govuk_frontend_jinja_overrides/templates/components/*/template.html`"
          "are all structurally-correct and up-to-date macros. If not, update the macros or retire them and update the "
          "rendering process."
      )
  
subject: Fix test description: njk -> html