Bump django from 2.2.21 to 2.2.22 in /requirements

Bumps [django](https://github.com/django/django) from 2.2.21 to 2.2.22.
- [Release notes](https://github.com/django/django/releases)
- [Commits](django/django@2.2.21...2.2.22)

---
updated-dependencies:
- dependency-name: django
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

requirements/base.txt

@@ -1,6 +1,6 @@
 # Bleeding edge Django
 
-django==2.2.21
+django==2.2.22
 
 # Configuration
 django-environ==0.4.5