Bump waitress from 1.3.0 to 1.3.1

Bumps [waitress](https://github.com/Pylons/waitress) from 1.3.0 to 1.3.1.
- [Release notes](https://github.com/Pylons/waitress/releases)
- [Changelog](https://github.com/Pylons/waitress/blob/master/HISTORY.txt)
- [Commits](Pylons/waitress@v1.3.0...v1.3.1)

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

requirements.txt

@@ -32,7 +32,7 @@ translationstring==1.3
 ujson==1.35
 urllib3==1.25.3
 venusian==1.2.0
-waitress==1.3.0
+waitress==1.3.1
 WebOb==1.8.5
 zope.deprecation==4.4.0
 zope.interface==4.6.0