Bump django from 2.2.4 to 2.2.28

Bumps [django](https://github.com/django/django) from 2.2.4 to 2.2.28.
- [Release notes](https://github.com/django/django/releases)
- [Commits](django/django@2.2.4...2.2.28)

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

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

Author: dependabot[bot]

Pipfile

@@ -6,7 +6,7 @@ verify_ssl = true
 [dev-packages]
 
 [packages]
-django = "==2.2.4"
+django = "==2.2.28"
 gunicorn = "*"
 dj-database-url = "*"
 psycopg2-binary = "*"