test(proxy): import LoginThrottle under TYPE_CHECKING for the throttle helper annotation

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

tests/test_litellm/proxy/auth/test_login_utils.py

@@ -8,11 +8,14 @@ to login_utils.py for better reusability.
 import os
 from collections.abc import Mapping
 from contextlib import ExitStack
-from typing import Final
+from typing import TYPE_CHECKING, Final
 from unittest.mock import AsyncMock, MagicMock, patch
 
 import pytest
 
+if TYPE_CHECKING:
+    from litellm.proxy.auth.login_throttle import LoginThrottle
+
 
 def _unlimited_throttle():
     """A throttle wired to real in-memory stores with limits no test can reach."""