fix: tests explictly set mock client to privacy false

Author: k11kirky

posthog/test/ai/langchain/test_callbacks.py

@@ -20,6 +20,7 @@
 @pytest.fixture(scope="function")
 def mock_client():
     with patch("posthog.client.Client") as mock_client:
+        mock_client.privacy_mode = False
         yield mock_client