Add syg to COMMON_OWNERS

Change-Id: Ib72254dfa29a8f875febb147b63c9681cd34e83b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2063413Reviewed-by: Shu-yu Guo <syg@chromium.org>
Commit-Queue: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66358}

COMMON_OWNERS

@@ -29,6 +29,7 @@ petermarshall@chromium.org
 rmcilroy@chromium.org
 sigurds@chromium.org
 solanes@chromium.org
+syg@chromium.org
 szuend@chromium.org
 tebbi@chromium.org
 titzer@chromium.org