Add cron workflow.

Author: Michael Howitz

.github/workflows/test.yml

@@ -6,6 +6,10 @@ on:
   pull_request:
     branches: [ master ]
     type: [ "opened", "reopened", "synchronize" ]
+  schedule:
+    - cron: '0 12 * * 0'  # run once a week on Sunday
+  # Allow to run this workflow manually from the Actions tab
+  workflow_dispatch:
 
 env:
   FORCE_COLOR: 1