Bump django from 2.2.21 to 2.2.22 in /days/069-072-django-rest/demo

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] <support@github.com>

Author: dependabot[bot]

days/069-072-django-rest/demo/requirements.txt

@@ -1,4 +1,4 @@
-django==2.2.21
+django==2.2.22
 django-registration==3.1.2
 djangorestframework
 requests