Update ollama.mdx (#1352)

fixed some problem

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---------

Co-authored-by: Mason Daugherty <mason@langchain.dev>

Author: fredricen

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

@@ -265,7 +265,8 @@ Some models, such as IBM's [Granite 3.2](https://ollama.com/library/granite3.2),
 To access Granite 3.2's thinking features, pass a message with a `"control"` role with content set to `"thinking"`. Because `"control"` is a non-standard message role, we can use a [ChatMessage](https://python.langchain.com/api_reference/core/messages/langchain_core.messages.chat.ChatMessage.html) object to implement it:
 
 ```python
-from langchain.messages import ChatMessage, HumanMessage
+from langchain.messages import HumanMessage
+from langchain_core.messages import ChatMessage
 from langchain_ollama import ChatOllama
 
 llm = ChatOllama(model="granite3.2:8b")