python: Import F, Q, QuerySet from their canonical module.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

zerver/lib/cache.py

@@ -25,8 +25,7 @@ from typing import (
 from django.conf import settings
 from django.core.cache import caches
 from django.core.cache.backends.base import BaseCache
-from django.db.models import Q
-from django.db.models.query import QuerySet
+from django.db.models import Q, QuerySet
 from django.http import HttpRequest
 from typing_extensions import ParamSpec