chore(deps): bump tornado from 6.4.1 to 6.4.2 in /docs (#221)

Bumps [tornado](https://github.com/tornadoweb/tornado) from 6.4.1 to 6.4.2.
- [Changelog](https://github.com/tornadoweb/tornado/blob/v6.4.2/docs/releases.rst)
- [Commits](tornadoweb/tornado@v6.4.1...v6.4.2)

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

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

Author: dependabot[bot]

docs/requirements.in

@@ -9,6 +9,6 @@ mock
 autodoc
 
 defusedxml
-tornado==6.4.1
+tornado==6.4.2
 jinja2==3.1.4
 idna==3.7

docs/requirements.txt

@@ -88,7 +88,7 @@ sphinxcontrib-qthelp==1.0.3
     # via sphinx
 sphinxcontrib-serializinghtml==1.1.9
     # via sphinx
-tornado==6.4.1
+tornado==6.4.2
     # via
     #   -r requirements.in
     #   livereload