fix anthropic bug (#2161)

### What problem does this PR solve?

#2159 fix anthropic bug

### Type of change

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

Co-authored-by: Zhedong Cen <[email protected]>

rag/llm/__init__.py

@@ -106,7 +106,7 @@ ChatModel = {
     "Tencent Hunyuan": HunyuanChat,
     "XunFei Spark": SparkChat,
     "BaiduYiyan": BaiduYiyanChat,
-    "Anthropic": VoyageChat,
+    "Anthropic": AnthropicChat,
 }