If it gives you the update prompt too bad, you should have installed menuhax when you could.
If not, (straight from plailect's guide):
10.7.0 - 11.0.0: Block the browser version check
- Set your primary DNS to107.211.140.065 before launching the browser so as not to trigger the browser version check.
- If on this browser version, you ever receive a message to update your browser, it is because your browser has detected it is not running the latest version.
- Once this message appears for the first time, it is impossible to get rid of it so you must use a non-browser entrypoint.