build!: update library to use Node 12 (#644)

* build!: Update library to use Node 12
Co-authored-by: Summer Ji <summerji@google.com>
Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: 3 people

handwritten/error-reporting/.github/sync-repo-settings.yaml

@@ -9,9 +9,9 @@ branchProtectionRules:
       - "ci/kokoro: System test"
       - docs
       - lint
-      - test (10)
       - test (12)
       - test (14)
+      - test (16)
       - cla/google
       - windows
       - OwlBot Post Processor