update OWNERS for vts related projects

Bug: none
Test: none
Change-Id: Ief57a5e6924f71ca6b2a9b54496cd4b5f315f373
diff --git a/OWNERS b/OWNERS
index 9fbcb47..1d7a8e1 100644
--- a/OWNERS
+++ b/OWNERS
@@ -3,3 +3,4 @@
 malchev@google.com
 smoreland@google.com
 yim@google.com  # vts tests
+guangzhu@google.com # vts tests