chore(deps): bump tornado from 6.1 to 6.3.2 in /docs (#175)

Bumps [tornado](https://github.com/tornadoweb/tornado) from 6.1 to 6.3.2.
- [Changelog](https://github.com/tornadoweb/tornado/blob/master/docs/releases.rst)
- [Commits](tornadoweb/tornado@v6.1.0...v6.3.2)

---
updated-dependencies:
- dependency-name: tornado
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

docs/requirements.txt

@@ -78,7 +78,7 @@ sphinxcontrib-qthelp==1.0.3
     # via sphinx
 sphinxcontrib-serializinghtml==1.1.5
     # via sphinx
-tornado==6.1
+tornado==6.3.2
     # via livereload
 urllib3==1.26.7
     # via requests