add pull request reference

Author: tmszi

Pipfile

@@ -83,6 +83,7 @@ django-filter = "*"
 django-js-urls = "*"
 mkdocs = "*"
 cairosvg = "*"
+# https://github.com/django/django/pull/12107
 django = {editable = true,git = "https://github.com/tmszi/django.git",ref = "ticket_31000_stable_2.2.x"}
 
 [dev-packages]