oss(contributing): update the example in the KServe documentation

Author: schneidermr

src/oss/python/integrations/chat/kserve.mdx

@@ -106,7 +106,7 @@ asyncio.run(main())
 Tool calling works with OpenAI-compatible endpoints.
 
 ```python
-from langchain_core.tools import tool
+from langchain.tools import tool
 
 @tool
 def get_weather(city: str) -> str:
@@ -137,7 +137,7 @@ print(result)
 ```python
 import base64
 import pathlib
-from langchain_core.messages import HumanMessage
+from langchain.messages import HumanMessage
 
 image_data = base64.b64encode(pathlib.Path("chart.png").read_bytes()).decode()