build: clean up untagged GHCR images

.github/workflows/ghcr-cleanup.yml

@@ -0,0 +1,19 @@
+name: Clean up untagged GHCR images
+
+on:
+  push:
+    branches:
+      - cleanup-ghcr
+  workflow_dispatch:
+
+jobs:
+  ghcr-cleanup:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: quartx-analytics/ghcr-cleaner@v1
+        with:
+          owner-type: user
+          token: ${{ secrets.GITHUB_TOKEN }}
+          repository-owner: ${{ github.repository_owner }}
+          package-name: jsrat-frontend
+          delete-untagged: true