meta: update last name for jkrems

Also adds current work email to mailmap.

PR-URL: nodejs#57006
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Jordan Harband <ljharb@gmail.com>
Reviewed-By: Jason Zhang <xzha4350@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>

.mailmap

@@ -240,7 +240,8 @@ James Ide <ide@jameside.com> <ide@users.noreply.github.com>
 James M Snell <jasnell@gmail.com>
 James Nimlos <james@nimlos.com>
 James Sumners <james@sumners.email> <james.sumners@gmail.com>
-Jan Krems <jan.krems@gmail.com> <jan.krems@groupon.com>
+Jan Martin <jan.krems@gmail.com>
+Jan Martin <jan.krems@gmail.com> <jankrems@google.com>
 Jem Bezooyen <github@jem.dev> <jem@hipmedia.ca>
 Jem Bezooyen <github@jem.dev> <jem@sendwithus.com>
 Jenna Vuong <jennavuong@gmail.com> <hello@jennavuong.com>

README.md

@@ -358,7 +358,7 @@ For information about the governance of the Node.js project, see
 * [jazelly](https://github.com/jazelly) -
   **Jason Zhang** <<xzha4350@gmail.com>> (he/him)
 * [jkrems](https://github.com/jkrems) -
-  **Jan Krems** <<jan.krems@gmail.com>> (he/him)
+  **Jan Martin** <<jan.krems@gmail.com>> (he/him)
 * [joyeecheung](https://github.com/joyeecheung) -
   **Joyee Cheung** <<joyeec9h3@gmail.com>> (she/her)
 * [juanarbol](https://github.com/juanarbol) -