Bump tornado in /blog-examples/llama-index/hacknernews_app

Bumps [tornado](https://github.com/tornadoweb/tornado) from 6.4 to 6.4.2.
- [Changelog](https://github.com/tornadoweb/tornado/blob/v6.4.2/docs/releases.rst)
- [Commits](tornadoweb/tornado@v6.4.0...v6.4.2)

---
updated-dependencies:
- dependency-name: tornado
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

blog-examples/llama-index/hacknernews_app/requirements.txt

@@ -182,7 +182,7 @@ toml==0.10.2
 tomli==2.0.1
 tomlkit==0.12.3
 toolz==0.12.1
-tornado==6.4
+tornado==6.4.2
 tqdm==4.66.3
 traitlets==5.14.1
 tree-sitter==0.20.4