fix example pipeline execution

Author: CongkeChen

examples/langgraph_agent/agent/agent.py

@@ -80,8 +80,9 @@ def build_graph_with_subgraph():
     api_key, url, model_name = get_model_config()
     model = init_chat_model(
         model_name,
+        model_provider="openai",
         api_key=api_key,
-        api_base=url,
+        base_url=url,
     )
 
     # Build calculator subgraph
@@ -127,8 +128,9 @@ def build_graph():
     api_key, url, model_name = get_model_config()
     model = init_chat_model(
         model_name,
+        model_provider="openai",
         api_key=api_key,
-        api_base=url,
+        base_url=url,
     )
 
     tools = [calculate]