Feat: Alter flask to Quart for async API serving. (#11275)

### What problem does this PR solve?

#11277

### Type of change

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

api/db/services/document_service.py

@@ -41,6 +41,7 @@ from rag.utils.redis_conn import REDIS_CONN
 from rag.utils.doc_store_conn import OrderByExpr
 from common import settings
 
+
 class DocumentService(CommonService):
     model = Document