circleCI config add chron job to test the build job every 15 minutes

.circleci/config.yml

@@ -133,3 +133,19 @@ workflows:
                 - develop
                 - /^hotfix\/.*/
                 - /^release\/.*/
+  test-build-cron:
+    triggers:
+      - schedule: # every 15 minutes
+          cron: "0,15,30.45 * * * *"
+          filters:
+            branches:
+              only: circleci-project-setup
+    jobs:
+      - build-staging:
+          context:
+            - scratch-www-all
+            - scratch-www-staging
+          filters:
+            branches:
+              only:
+                - circleci-project-setup # remove this before releasing