add django stubs for HistoricForeignKey

Author: david-homelend

simple_history/models.py

@@ -3,6 +3,7 @@
 import uuid
 import warnings
 from functools import partial
+from typing import TypeVar
 
 from django.apps import apps
 from django.conf import settings
@@ -45,6 +46,13 @@
 except ImportError:
     from threading import local as LocalContext
 
+
+# __set__ value type
+_ST = TypeVar("_ST")
+# __get__ return type
+_GT = TypeVar("_GT")
+
+
 registered_models = {}
 
 
@@ -873,7 +881,7 @@ def get_queryset(self):
         )
 
 
-class HistoricForeignKey(ForeignKey):
+class HistoricForeignKey(ForeignKey[_ST, _GT]):
     """
     Allows foreign keys to work properly from a historic instance.