Bump django-registration from 3.0.1 to 3.1.2

Bumps [django-registration](https://github.com/ubernostrum/django-registration) from 3.0.1 to 3.1.2.
- [Release notes](https://github.com/ubernostrum/django-registration/releases)
- [Commits](https://github.com/ubernostrum/django-registration/compare/3.0.1...3.1.2)

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

requirements.txt

@@ -6,7 +6,7 @@ django-anymail[mailgun]==7.0.0
 django-cors-headers==3.2.0
 django-prometheus==2.0.0
 django-redis==4.11.0
-django-registration==3.0.1
+django-registration==3.1.2
 django-storages==1.8.0
 gunicorn==20.0.4
 huey==2.1.3