Bump requests from 2.21.0 to 2.22.0

Bumps [requests](https://github.com/requests/requests) from 2.21.0 to 2.22.0.
- [Release notes](https://github.com/requests/requests/releases)
- [Changelog](https://github.com/kennethreitz/requests/blob/master/HISTORY.md)
- [Commits](psf/requests@v2.21.0...v2.22.0)

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

requirements.txt

@@ -28,7 +28,7 @@ pyramid-tm==2.2.1
 pyrsistent==0.15.2
 python-dateutil==2.8.0
 repoze.sendmail==4.4.1
-requests==2.21.0
+requests==2.22.0
 simplejson==3.16.0
 six==1.12.0
 transaction==2.4.0