Bump django from 2.2.10 to 2.2.13

Bumps [django](https://github.com/django/django) from 2.2.10 to 2.2.13.
- [Release notes](https://github.com/django/django/releases)
- [Commits](django/django@2.2.10...2.2.13)

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

Author: dependabot[bot]

requirements.txt

@@ -3,7 +3,7 @@ certifi==2019.9.11
 chardet==3.0.4
 cycler==0.10.0
 dj-database-url==0.5.0
-Django==2.2.10
+Django==2.2.13
 django-heroku==0.3.1
 googletrans==2.4.0
 gunicorn==19.9.0