fix typing

Author: provinzkraut

src/pytest_databases/_service.py

@@ -6,7 +6,8 @@
 import subprocess  # noqa: S404
 import time
 from contextlib import AbstractContextManager, contextmanager
-from typing import TYPE_CHECKING, Any, Callable, Generator, Self
+from typing import TYPE_CHECKING, Any, Callable, Generator
+from typing_extensions import Self
 
 import filelock
 import pytest