[workflow] add clean ghcr to remove old dev imsages

.github/workflows/on-push-main.yml

@@ -53,3 +53,15 @@ jobs:
             ghcr.io/${{ github.repository }}:${{ steps.git.outputs.image_tag }}
             ghcr.io/${{ github.repository }}:development
 
+      - name: Delete old dev images
+        uses: snok/container-retention-policy@v2
+        with:
+          image-names: gantry
+          cut-off: One day ago UTC
+          account-type: personal
+          token: ${{ secrets.TOKEN_DELETE_GHCR_IMAGES }}
+          keep-at-least: 5
+          skip-tags: latest, development
+          filter-tags: "dev-*"
+          dry-run: False
+