Update docker/build-push-action action to v6

Author: renovate[bot]

.github/workflows/build-docker.yaml

@@ -19,7 +19,7 @@ jobs:
           username: ${{ secrets.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_TOKEN }}
       - name: Build and push
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           push: true
           platforms: linux/amd64,linux/arm64