Switch to every 8 hours (#300)

Author: kddejong

.github/workflows/template-schema-updater.yaml

@@ -1,7 +1,7 @@
 name: Update CloudFormation schemas
 on:
   schedule:
-    - cron: '*/8 * * * *'
+    - cron: '0 */8 * * *'
   workflow_dispatch: # Enables on-demand/manual triggering: https://docs.github.com/en/free-pro-team@latest/actions/managing-workflow-runs/manually-running-a-workflow
 jobs:
   schema-updater: