Fix keys of Xinference deployed models, especially has the same model name with public hosted models. (#2832)

### What problem does this PR solve?

Fix keys of Xinference deployed models, especially has the same model
name with public hosted models.

### Type of change

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

---------

Co-authored-by: 0000sir <0000sir@gmail.com>
Co-authored-by: Kevin Hu <kevinhu.sh@gmail.com>

rag/llm/rerank_model.py

@@ -162,7 +162,8 @@ class XInferenceRerank(Base):
         self.base_url = base_url
         self.headers = {
             "Content-Type": "application/json",
-            "accept": "application/json"
+            "accept": "application/json",
+            "Authorization": f"Bearer {key}"
         }
 
     def similarity(self, query: str, texts: list):