Use the new headless Chrome on the pre-registered driver (#2726)

Earlier this year (2023), Chrome released Chrome for Testing, a new
Chrome flavor that targets the testing and automation use cases. This
flavor is accessible using the `--headless=new` option since Chrome 109,
released January 1, 2023. This new mode supports the full browser
capabilities, including running extensions.

The default headless mode is still pointed to `--headless=old` for now,
but it's planned to be changed to `new` over time.

This commit explicitly chooses the `new` headless mode, that uses Chrome
for Testing.

lib/capybara/registrations/drivers.rb

@@ -32,7 +32,7 @@
   version = Capybara::Selenium::Driver.load_selenium
   options_key = Capybara::Selenium::Driver::CAPS_VERSION.satisfied_by?(version) ? :capabilities : :options
   browser_options = Selenium::WebDriver::Chrome::Options.new.tap do |opts|
-    opts.add_argument('--headless')
+    opts.add_argument('--headless=new')
     opts.add_argument('--disable-gpu') if Gem.win_platform?
     # Workaround https://bugs.chromium.org/p/chromedriver/issues/detail?id=2650&q=load&sort=-id&colspec=ID%20Status%20Pri%20Owner%20Summary
     opts.add_argument('--disable-site-isolation-trials')