Bump Chizkiyahu/delete-untagged-ghcr-action in /.github/workflows

Bumps [Chizkiyahu/delete-untagged-ghcr-action](https://github.com/chizkiyahu/delete-untagged-ghcr-action) from 4 to 6.
- [Release notes](https://github.com/chizkiyahu/delete-untagged-ghcr-action/releases)
- [Commits](Chizkiyahu/delete-untagged-ghcr-action@v4...v6)

---
updated-dependencies:
- dependency-name: Chizkiyahu/delete-untagged-ghcr-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/docker.yaml

@@ -76,7 +76,7 @@ jobs:
 
       - name: Delete untagged images from GitHub Container Registry
         continue-on-error: true
-        uses: Chizkiyahu/delete-untagged-ghcr-action@v4
+        uses: Chizkiyahu/delete-untagged-ghcr-action@v6
         with:
           token: ${{ secrets.PAT_GHCR_CLEANUP }}
           package_name: ${{ github.event.repository.name }}