Install django-extensions

This is needed for `reset_demo` to work

requirements/base.txt

@@ -3,3 +3,4 @@ django-dotenv==1.4.1
 wagtail>=4.1,<5
 wagtail-font-awesome-svg>=0.0.3,<1
 django-debug-toolbar>=3.2,<4
+django-extensions==3.2.1