Update container image cleanup GitHub actions

Switch to dataaxiom/ghcr-cleanup-action which treats multi-arch images
correctly and refactor the cleanup jobs so that we delete untagged
versions once a day from Monday to Friday and delete PR tags once the PR
is closed (merged or unmerged).

.github/workflows/gitlab-container-image-cleanup-pr-tag.yml

@@ -0,0 +1,21 @@
+---
+name: Delete closed PR container image tag
+
+"on":
+  pull_request:
+    types:
+      - closed
+
+jobs:
+  cleanup-pr-tag:
+    uses: ubuntu-latest
+    steps:
+      - name: Set image version for PR to branch name
+        run: echo "VERSION=${GITHUB_HEAD_REF//\//-}" >> ${GITHUB_ENV}
+
+      - name: Delete PR container image tag
+        uses: dataaxiom/ghcr-cleanup-action@v1
+        with:
+          tags: ${{ env.VERSION }}
+          package: ${{ github.event.repository.name }}/gitlab
+          token: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/prune-old-container-images.yml

@@ -1,5 +1,5 @@
 ---
-name: Prune old container images
+name: Prune untagged container images
 
 "on":
   schedule:
@@ -10,10 +10,8 @@ jobs:
   prune:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/delete-package-versions@v5
+      - uses: dataaxiom/ghcr-cleanup-action@v1
         with:
-          package-name: "${{ github.repository }}-gitlab"
-          package-type: container
-          # never delete release versions or latest
-          ignore-versions: "^(v.*|latest)$"
-          min-versions-to-keep: 3
+          token: ${{ secrets.GITHUB_TOKEN }}
+          package: ${{ github.event.repository.name }}/gitlab
+          validate: true