Fix: base url issue. (#8281)

### What problem does this PR solve?


### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

rag/llm/chat_model.py

     def __init__(self, key, model_name, base_url=None, **kwargs):
         super().__init__(key, model_name, base_url=base_url, **kwargs)
 
-        self.client = Client(host=kwargs["base_url"]) if not key or key == "x" else Client(host=kwargs["base_url"], headers={"Authorization": f"Bearer {key}"})
+        self.client = Client(host=base_url) if not key or key == "x" else Client(host=base_url, headers={"Authorization": f"Bearer {key}"})
         self.model_name = model_name
 
     def _clean_conf(self, gen_conf):