Bump tornado from 6.4 to 6.4.2

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] <support@github.com>

requirements.txt

@@ -101,7 +101,7 @@ SQLAlchemy==2.0.28
 structlog==24.1.0
 tblib==3.0.0
 toolz==0.12.1
-tornado==6.4
+tornado==6.4.2
 tqdm==4.66.2
 trollimage==1.23.1
 trollsift==0.5.1