ref: add row type to our custom QuerySet (#73589)

this matches the signature and generics from `django-stubs`

<!-- Describe your PR here. -->

src/sentry/db/models/manager/base_query_set.py

@@ -7,11 +7,11 @@
 from django.db import connections, router, transaction
 from django.db.models import QuerySet, sql
 
-from sentry.db.models.manager.types import M
+from sentry.db.models.manager.types import M, R
 from sentry.signals import post_update
 
 
-class BaseQuerySet(QuerySet[M]):
+class BaseQuerySet(QuerySet[M, R]):
     def __init__(self, *args: Any, **kwargs: Any) -> None:
         super().__init__(*args, **kwargs)
         self._with_post_update_signal = False

src/sentry/db/models/manager/types.py

@@ -1,7 +1,7 @@
 from __future__ import annotations
 
-from typing import TypeVar
-
 from django.db.models import Model
+from typing_extensions import TypeVar
 
 M = TypeVar("M", bound=Model, covariant=True)
+R = TypeVar("R", covariant=True, default=M)