Bump django from 3.1.12 to 3.1.13

Bumps [django](https://github.com/django/django) from 3.1.12 to 3.1.13. - [Release notes](https://github.com/django/django/releases) - [Commits](django/django@3.1.12...3.1.13) --- updated-dependencies: - dependency-name: django dependency-type: direct:production ... Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements.txt

@@ -1,7 +1,7 @@
 asn1crypto==0.24.0
 beautifulsoup4==4.8.2
 dj-database-url==0.5.0
-Django==3.1.12
+Django==3.1.13
 django-heroku==0.3.1
 django-widget-tweaks==1.4.3
 gunicorn==20.0.4