Bump waitress from 1.4.4 to 2.0.0

Bumps [waitress](https://github.com/Pylons/waitress) from 1.4.4 to 2.0.0.
- [Release notes](https://github.com/Pylons/waitress/releases)
- [Changelog](https://github.com/Pylons/waitress/blob/master/CHANGES.txt)
- [Commits](Pylons/waitress@v1.4.4...v2.0.0)

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

requirements.txt

@@ -37,7 +37,7 @@ typing==3.7.4.3
 ujson==4.0.2
 urllib3==1.26.3
 venusian==3.0.0
-waitress==1.4.4
+waitress==2.0.0
 WebOb==1.8.7
 zope.deprecation==4.4.0
 zope.interface==5.2.0