Fix a bug in VolcEngine (#3658)

### What problem does this PR solve?

Fix a bug in VolcEngine  #3553

### Type of change

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

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

rag/llm/__init__.py

@@ -48,6 +48,7 @@ EmbeddingModel = {
     "BaiduYiyan": BaiduYiyanEmbed,
     "Voyage AI": VoyageEmbed,
     "HuggingFace": HuggingFaceEmbed,
+    "VolcEngine":VolcEngineEmbed,
 }
 
 CvModel = {

rag/llm/embedding_model.py

@@ -718,3 +718,10 @@ class HuggingFaceEmbed(Base):
         else:
             raise Exception(f"Error: {response.status_code} - {response.text}")
 
+class VolcEngineEmbed(OpenAIEmbed):
+    def __init__(self, key, model_name, base_url="https://ark.cn-beijing.volces.com/api/v3"):
+        if not base_url:
+            base_url = "https://ark.cn-beijing.volces.com/api/v3"
+        ark_api_key = json.loads(key).get('ark_api_key', '')
+        model_name = json.loads(key).get('ep_id', '') + json.loads(key).get('endpoint_id', '')
+        super().__init__(ark_api_key,model_name,base_url)