Renovate: Update docker/metadata-action action to v6

Author: renovate[bot]

.github/workflows/container-registry-ghcr.yaml

@@ -30,7 +30,7 @@ jobs:
           username: ${{ github.actor }}
       - name: Extract metadata (tags, labels) for Docker
         id: meta
-        uses: docker/metadata-action@v5
+        uses: docker/metadata-action@v6
         with:
           images: ghcr.io/${{ github.repository }}
           tags: |