support gpt-4o (#773)

### What problem does this PR solve?
#771 

### Type of change

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

rag/llm/__init__.py

@@ -25,7 +25,8 @@ EmbeddingModel = {
     "Tongyi-Qianwen": DefaultEmbedding, #QWenEmbed,
     "ZHIPU-AI": ZhipuEmbed,
     "FastEmbed": FastEmbed,
-    "Youdao": YoudaoEmbed
+    "Youdao": YoudaoEmbed,
+    "DeepSeek": DefaultEmbedding
 }