dry run image retention

.github/workflows/image-retention.yaml

@@ -0,0 +1,24 @@
+name: Delete old container images
+
+on:
+  #schedule:
+  #  - cron: "15 * * * *" # every day at midnight
+  push:
+    branches:
+      - container-registry-retention
+
+jobs:
+  clean-ghcr:
+    name: Delete old unused container images
+    runs-on: ubuntu-latest
+    steps:
+      - name: Delete 'dev' containers older than a week
+        uses: snok/container-retention-policy@v2
+        with:
+          image-names: scanserver
+          cut-off: 6 month ago UTC
+          account-type: org
+          org-name: GDATASoftwareAG
+          keep-at-least: 5
+          dry-run: false
+          token: ${{ secrets.PAT_CONTAINER_REGISTRY }}