Update options so the new chrome driver version 120 will work

Within our cucumber tests, fetching logs from the driver seems to be broken with the new chrome version 119 -> 120 upgrade.
This issue seems to be solved in this github issue thread by updating the options to '--headless=new'
SeleniumHQ/selenium#13112

lib/govuk_test.rb

@@ -18,7 +18,7 @@ def self.configure
 
   def self.headless_chrome_selenium_options
     Selenium::WebDriver::Chrome::Options.new.tap do |options|
-      options.add_argument("--headless")
+      options.add_argument("--headless=new")
       options.add_argument("--no-sandbox") if ENV["GOVUK_TEST_CHROME_NO_SANDBOX"]
     end
   end

spec/govuk_test_spec.rb

@@ -23,7 +23,7 @@
       options = described_class.headless_chrome_selenium_options
 
       expect(options).to be_instance_of(Selenium::WebDriver::Chrome::Options)
-      expect(options.args).to include("--headless")
+      expect(options.args).to include("--headless=new")
     end
 
     it "can be configured with an environment variable to run in no-sandbox" do