doc: use npm team for npm upgrades in collaborator guide

The collaborator guide suggests pinging individuals about npm upgrades.
Change to pinging the npm team instead.

PR-URL: https://github.com/nodejs/node/pull/33999


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Andrey Pechkurov <apechkurov@gmail.com>