[owners] Add myself to src/execution/OWNERS.

Bug: none
Change-Id: Idef3596192deb3dfe66e500d3f9ff2560b113649
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3361836
Auto-Submit: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78456}

src/execution/OWNERS

+bmeurer@chromium.org
 ishell@chromium.org
 jgruber@chromium.org
 jkummerow@chromium.org