[Security] Bump requests from 2.18.4 to 2.20.0

Bumps [requests](https://github.com/requests/requests) from 2.18.4 to 2.20.0. **This update includes security fixes.**
- [Release notes](https://github.com/requests/requests/releases)
- [Changelog](https://github.com/requests/requests/blob/master/HISTORY.md)
- [Commits](psf/requests@v2.18.4...v2.20.0)

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

setup.py

@@ -48,7 +48,7 @@
         'ffs>=0.0.8.2',
         'letter==0.4.1',
         'jinja2==2.10',
-        'requests==2.18.4',
+        'requests==2.20.0',
         'django==1.10.8',
         'django-reversion==1.10.2',
         'django-axes==1.7.0',

test-requirements.txt

@@ -6,5 +6,5 @@ coveralls
 celery==3.1.25
 django-celery==3.2.2
 flake8==3.2.1
-requests==2.18.4
+requests==2.20.0
 psycopg2==2.7