[4.1.x] Refs #33646 -- Moved tests of QuerySet async interface into async tests.

Backport of e580b891cb from main

tests/async/models.py

@@ -1,5 +1,11 @@
 from django.db import models
+from django.utils import timezone
+
+
+class RelatedModel(models.Model):
+    simple = models.ForeignKey("SimpleModel", models.CASCADE, null=True)
 
 
 class SimpleModel(models.Model):
     field = models.IntegerField()
+    created = models.DateTimeField(default=timezone.now)