meta: add mailmap entry for Ethan-Arrowood

The next update-authors.js run will add a second entry to AUTHORS for
Ethan-Arrowood because they use a new email address in a commit they
authored very recently. Add the new email address to mailmap and update
AUTHORS.

PR-URL: https://github.com/nodejs/node/pull/39930


Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Zijian Liu <lxxyxzj@gmail.com>