Bump waitress from 1.4.4 to 2.1.1

Bumps [waitress](https://github.com/Pylons/waitress) from 1.4.4 to 2.1.1.
- [Release notes](https://github.com/Pylons/waitress/releases)
- [Changelog](https://github.com/Pylons/waitress/blob/master/CHANGES.txt)
- [Commits](Pylons/waitress@v1.4.4...v2.1.1)

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

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

Author: dependabot[bot]

requirements.txt

@@ -68,6 +68,6 @@ tqdm==4.48.0
 typed-ast==1.4.1
 typing-extensions==3.7.4.2
 urllib3==1.26.5
-waitress==1.4.4
+waitress==2.1.1
 websocket-client==0.57.0
 Werkzeug==1.0.1