Update docker/metadata-action action to v6 (#477)

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

Author: renovate[bot]

.github/workflows/docker-image.yml

@@ -26,7 +26,7 @@ jobs:
 
       - name: Extract metadata
         id: metadata
-        uses: docker/metadata-action@v5
+        uses: docker/metadata-action@v6
         with:
           images: |
             rob93c/stickerify