Add new owner to branch cut artifact

Change-Id: I34cc92cf75e242db5a0873635989c097afd245bf
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3564563Reviewed-by: Lutz Vahl <vahl@chromium.org>
Commit-Queue: Liviu Rau <liviurau@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79708}

gni/OWNERS

@@ -2,3 +2,4 @@ file:../INFRA_OWNERS
 
 per-file v8.cmx=victorgomes@chromium.org
 per-file release_branch_toggle.gni=v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com
+per-file release_branch_toggle.gni=vahl@chromium.org
\ No newline at end of file