Bump waitress from 2.0.0 to 2.1.0 (#489)

Bumps [waitress](https://github.com/Pylons/waitress) from 2.0.0 to 2.1.0.
- [Release notes](https://github.com/Pylons/waitress/releases)
- [Changelog](https://github.com/Pylons/waitress/blob/master/CHANGES.txt)
- [Commits](Pylons/waitress@v2.0.0...v2.1.0)

---
updated-dependencies:
- dependency-name: waitress
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements.txt

@@ -35,7 +35,7 @@ translationstring==1.4
 ujson==5.1.0
 urllib3==1.26.8
 venusian==3.0.0
-waitress==2.0.0
+waitress==2.1.0
 WebOb==1.8.7
 zope.deprecation==4.4.0
 zope.interface==5.4.0