build: allow "zone.js" as scope for commit messages (#31277)

Adds `zone.js` as valid scope for commit messages. This
is necessary because the `zone.js` repository has been
moved into the mono-repo and future changes should be
categorized properly through commit messages.

Currently the pre-commit git hook or CircleCI will fail when
`zone.js` is used as commit scope.

PR Close #31277

tools/validate-commit-message/commit-message.json

@@ -36,6 +36,7 @@
     "service-worker",
     "upgrade",
     "packaging",
-    "changelog"
+    "changelog",
+    "zone.js"
   ]
 }