Bump python-dateutil from 2.8.0 to 2.8.1

Bumps [python-dateutil](https://github.com/dateutil/dateutil) from 2.8.0 to 2.8.1.
- [Release notes](https://github.com/dateutil/dateutil/releases)
- [Changelog](https://github.com/dateutil/dateutil/blob/master/NEWS)
- [Commits](dateutil/dateutil@2.8.0...2.8.1)

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

requirements.txt

@@ -16,7 +16,7 @@ psycopg2==2.8.4
 pycodestyle==2.5.0
 pycparser==2.19
 pycrypto==2.6.1
-python-dateutil==2.8.0
+python-dateutil==2.8.1
 raven==6.10.0
 pytz==2020.1
 rcssmin==1.0.6