Tornado dependency failing CI tests

[yadudoc]

The CI security checks are catching and reporting a security vulnerability in tornado. We could disable these tests temporarily as we no longer depend on tornado for the package requirements, and only for the test-requirements

More on this vulnerability here: tornadoweb/tornado#2981

Here's the notice from the security check:

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|          \____  $$ /$$__  $$| $$    | $$_____/  | $$ /$$| $$  | $$           |
|          /$$$$$$$/|  $$$$$$$| $$    |  $$$$$$$  |  $$$$/|  $$$$$$$           |
|         |_______/  \_______/|__/     \_______/   \___/   \____  $$           |
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|  by pyup.io                                              \______/            |
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+==============================================================================+
| REPORT                                                                       |
| checked 103 packages, using free DB (updated once a month)                   |
+============================+===========+==========================+==========+
| package                    | installed | affected                 | ID       |
+============================+===========+==========================+==========+
| tornado                    | 6.1       | <=6.1                    | 39462    |
+==============================================================================+
Error: Process completed with exit code 255.