Bump tornado from 6.4 to 6.4.1

Bumps [tornado](https://github.com/tornadoweb/tornado) from 6.4 to 6.4.1.
- [Changelog](https://github.com/tornadoweb/tornado/blob/master/docs/releases.rst)
- [Commits](tornadoweb/tornado@v6.4.0...v6.4.1)

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

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

requirements.txt

@@ -435,7 +435,7 @@ toml==0.10.2
     #   fmriprep
     #   fmriprep (pyproject.toml)
     #   sdcflows
-tornado==6.4
+tornado==6.4.1
     # via bokeh
 tqdm==4.66.1
     # via