ci(workflows): cleanup PR Docker images

.github/workflows/pull-request-cleanup.yml

@@ -0,0 +1,18 @@
+name: Pull Request Cleanup
+
+on:
+  pull_request:
+    types: [ closed ]
+
+permissions:
+  contents: read
+
+jobs:
+
+  cleanup:
+    name: Cleanup
+    uses: ./.github/workflows/__delete.yml
+    secrets: inherit
+    with:
+      gotenberg_version: pr-${{ github.event.pull_request.number }}
+      alternate_repository: snapshot