[Torque] Update owners file

Add nicohartmann@ as an owner.

Change-Id: I7c24b1ab575db857a15cff709f44c87c74106d80
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2593332Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Michael Stanton <mvstanton@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72048}

src/torque/OWNERS

-danno@chromium.org
-jarin@chromium.org
 mvstanton@chromium.org
-sigurds@chromium.org
-szuend@chromium.org
+nicohartmann@chromium.org
 tebbi@chromium.org