Update docker/metadata-action action to v6

Author: renovate[bot]

.github/workflows/docker-publish.yml

@@ -49,7 +49,7 @@ jobs:
       # https://github.com/docker/metadata-action
       - name: Extract Docker metadata
         id: meta
-        uses: docker/metadata-action@v5
+        uses: docker/metadata-action@v6
         with:
           images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}