Merge pull request #8173 from microsoft/dependabot/pip/tornado-6.5.6

Bump tornado from 6.5.5 to 6.5.6

Author: jenshnielsen

requirements.txt

@@ -433,7 +433,7 @@ toolz==1.1.0
     # via
     #   dask
     #   partd
-tornado==6.5.5
+tornado==6.5.6
     # via
     #   ipykernel
     #   jupyter-client