Bump tornado from 6.2 to 6.3.2

Bumps [tornado](https://github.com/tornadoweb/tornado) from 6.2 to 6.3.2.
- [Changelog](https://github.com/tornadoweb/tornado/blob/master/docs/releases.rst)
- [Commits](tornadoweb/tornado@v6.2.0...v6.3.2)

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

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements-CI.txt

@@ -157,7 +157,7 @@ svgwrite==1.4.3
 terminado==0.17.1
 tinycss2==1.2.1
 toolz==0.12.0
-tornado==6.2
+tornado==6.3.2
 tqdm==4.64.1
 traitlets==5.8.1
 git+https://github.com/tskit-dev/tsconvert@e99c837e4e26ccbf4f480a4c48626338eeff7dc3