add support for LM Studio (#1663)

### What problem does this PR solve?

#1602 

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

---------

Co-authored-by: Zhedong Cen <cenzhedong2@126.com>

rag/llm/rerank_model.py

@@ -202,3 +202,11 @@ class NvidiaRerank(Base):
         }
         res = requests.post(self.base_url, headers=self.headers, json=data).json()
         return (np.array([d["logit"] for d in res["rankings"]]), token_count)
+
+
+class LmStudioRerank(Base):
+    def __init__(self, key, model_name, base_url):
+        pass
+
+    def similarity(self, query: str, texts: list):
+        raise NotImplementedError("The LmStudioRerank has not been implement")