Update Yichat base_url (#2620)

### What problem does this PR solve?

Update Yichat base_url

### Type of change

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

Co-authored-by: liuhua <10215101452@stu.ecun.edu.cn>

rag/llm/chat_model.py

@@ -981,9 +981,9 @@ class SILICONFLOWChat(Base):
 
 
 class YiChat(Base):
-    def __init__(self, key, model_name, base_url="https://api.01.ai/v1"):
+    def __init__(self, key, model_name, base_url="https://api.lingyiwanwu.com/v1"):
         if not base_url:
-            base_url = "https://api.01.ai/v1"
+            base_url = "https://api.lingyiwanwu.com/v1"
         super().__init__(key, model_name, base_url)