Merge pull request #238 from tskit-dev/dependabot/pip/tornado-6.3.2

Bump tornado from 6.2 to 6.3.2

Author: benjeffery

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