Bump django from 2.1.7 to 2.2.13

Bumps [django](https://github.com/django/django) from 2.1.7 to 2.2.13.
- [Release notes](https://github.com/django/django/releases)
- [Commits](django/django@2.1.7...2.2.13)

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

requirements.txt

@@ -26,7 +26,7 @@ cryptography==2.7
 daphne==2.3.0
 defusedxml==0.6.0
 dj-database-url==0.5.0
-Django==2.1.7
+Django==2.2.13
 django-allauth==0.39.1
 django-cors-headers==3.0.2
 django-countries==5.3.3