chore: update Docker build action to v6 in nightly build workflow

- Upgraded the Docker build and push action from v5 to v6 to leverage improved performance and security features.
- This change ensures the nightly build workflow utilizes the latest optimizations available in the Docker action.

.github/workflows/nightly-build.yml

@@ -146,7 +146,7 @@ jobs:
             type=raw,value=nightly-{{date 'YYYYMMDD'}}
 
       - name: Build and push Docker image
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           context: .
           push: true