Remove myself from snapshot owners

Change-Id: Iceaba4dcb9f3bc457e03735a94b615764757a635
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2290854
Auto-Submit: Peter Marshall <petermarshall@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68780}

src/snapshot/OWNERS

 delphick@chromium.org
 jgruber@chromium.org
-petermarshall@chromium.org
 verwaest@chromium.org
 yangguo@chromium.org