Fix: rerank with YoudaoRerank issue. (#6396)

### What problem does this PR solve?

Fix rerank with YoudaoRerank issue，"'YoudaoRerank' object has no
attribute '_dynamic_batch_size'"


![17425412353825](https://github.com/user-attachments/assets/9ed304c7-317a-440e-acff-fe895fc20f07)


### Type of change

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

rag/llm/rerank_model.py

@@ -194,6 +194,8 @@ class YoudaoRerank(DefaultRerank):
                                 "maidalun1020", "InfiniFlow"))
 
         self._model = YoudaoRerank._model
+        self._dynamic_batch_size = 8
+        self._min_batch_size = 1
 
     def similarity(self, query: str, texts: list):
         pairs = [(query, truncate(t, self._model.max_length)) for t in texts]