Fix langchain tests.

Author: umaannamalai

tests/mlmodel_langchain/test_chain.py

@@ -483,8 +483,8 @@
             "response.headers.ratelimitResetRequests": "6ms",
             "response.headers.ratelimitResetTokens": "0s",
             "response.usage.prompt_tokens": 73,
-            "response.usage.completion_tokens": 375,
-            "response.usage.total_tokens": 448,
+            "response.usage.completion_tokens": 337,
+            "response.usage.total_tokens": 410,
             "response.number_of_messages": 3,
         },
     ],