ci: update docker/metadata-action action to v6 (#310)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/release-docker.yaml

@@ -36,7 +36,7 @@ jobs:
 
       - name: Docker metadata
         id: meta
-        uses: docker/metadata-action@v5
+        uses: docker/metadata-action@v6
         with:
           images: ${{ env.IMAGE }}
           tags: |