Switch to new chrome headless mode

Since version 112 chrome has a new headless mode [1]. By trial we found
the old mode causes low and unchangeable window size on MacOS, which made
some elements not clickable by Selenium. In new mode all elements were
clickable. This change lets all e2e tests run in new mode.

Chrome developers say regarding the new mode

> We intend to remove the old Headless from the Chrome binary and stop
> supporting this mode in Puppeteer in 2024.

seleniumbase --headless means old mode chrome --headless=chrome [2]
seleniumbase --headless2 means new mode chrome --headless=new [3]

[1] https://developer.chrome.com/docs/chromium/new-headless
[2] https://github.com/seleniumbase/SeleniumBase/blob/283c3db0228e30def2ca4f710d2d312a2bdae419/seleniumbase/core/browser_launcher.py#L1631
[3] https://github.com/seleniumbase/SeleniumBase/blob/283c3db0228e30def2ca4f710d2d312a2bdae419/seleniumbase/core/browser_launcher.py#L3278

tasks.py

@@ -232,7 +232,7 @@ def test_end2end(
 
     focus_argument = f"-k {focus}" if focus is not None else ""
     exit_first_argument = "--exitfirst" if exit_first else ""
-    headless_argument = "--headless" if headless else ""
+    headless_argument = "--headless2" if headless else ""
 
     test_command = f"""
         pytest