meta: move AnnaMag to Collaborator Emeriti list

AnnaMag hasn't authored/landed/reviewed code in quite some time. I sent
them an email asking about becoming Emeritus but did not get a response.
It's easy enough to re-onboard someone back to active status if they
become active again, so I think this is a pretty safe change to make.
I'll specifically request a review of this change from them so they get
notified and can comment/review/block/approve/etc. this.

PR-URL: https://github.com/nodejs/node/pull/27603


Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>