Add verwaest to parsing/OWNERS

Reason:
$ git log --author=verwaest --since="6 months ago" --oneline src/parsing

BUG=

Review-Url: https://codereview.chromium.org/2505623002
Cr-Commit-Position: refs/heads/master@{#41026}

src/parsing/OWNERS

@@ -4,4 +4,5 @@ adamk@chromium.org
 littledan@chromium.org
 marja@chromium.org
 rossberg@chromium.org
+verwaest@chromium.org
 vogelheim@chromium.org