chore(deps): update docker/build-push-action action to v6

Author: renovate[bot]

.github/workflows/docker-publish.yml

@@ -55,7 +55,7 @@ jobs:
             type=semver,pattern={{major}}
 
       - name: Build and push Docker image (multi-arch)
-        uses: docker/build-push-action@v4
+        uses: docker/build-push-action@v6
         with:
           context: .
           push: ${{ github.event_name != 'pull_request' }}