Update typing_extensions imports in third-party stubs (#11245)

stubs/google-cloud-ndb/google/cloud/ndb/_datastore_api.pyi

@@ -1,4 +1,4 @@
-from typing_extensions import Literal
+from typing import Literal
 
 EVENTUAL: Literal[2]
 EVENTUAL_CONSISTENCY: Literal[2]

stubs/google-cloud-ndb/google/cloud/ndb/model.pyi

@@ -1,8 +1,8 @@
 import datetime
 from _typeshed import Unused
 from collections.abc import Callable, Iterable, Sequence
-from typing import Any, NoReturn
-from typing_extensions import Literal, Self, TypeAlias
+from typing import Any, Literal, NoReturn
+from typing_extensions import Self, TypeAlias
 
 from google.cloud.ndb import exceptions, key as key_module, query as query_module, tasklets as tasklets_module