Bump django from 2.2.18 to 2.2.20 (#42)

Bumps [django](https://github.com/django/django) from 2.2.18 to 2.2.20.
- [Release notes](https://github.com/django/django/releases)
- [Commits](django/django@2.2.18...2.2.20)

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

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

requirements.txt

@@ -18,7 +18,7 @@ django-rq
 django-taggit
 django-taggit-templatetags
 django-user-agents
-django==2.2.18
+django==2.2.20
 djangorestframework
 h5py
 ipython