chore(deps): bump tornado in /docs in the pip group across 1 directory

Bumps the pip group with 1 update in the /docs directory: [tornado](https://github.com/tornadoweb/tornado).


Updates `tornado` from 6.5.2 to 6.5.5
- [Changelog](https://github.com/tornadoweb/tornado/blob/master/docs/releases.rst)
- [Commits](tornadoweb/tornado@v6.5.2...v6.5.5)

---
updated-dependencies:
- dependency-name: tornado
  dependency-version: 6.5.5
  dependency-type: indirect
  dependency-group: pip
...

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Author: dependabot[bot]