refactor: no need to inherit in python3 clean the code (#5659)

### What problem does this PR solve?

As title

### Type of change


- [x] Refactoring

Signed-off-by: yihong0618 <zouzou0208@gmail.com>

rag/utils/azure_sas_conn.py

@@ -24,7 +24,7 @@ from azure.storage.blob import ContainerClient
 
 
 @singleton
-class RAGFlowAzureSasBlob(object):
+class RAGFlowAzureSasBlob:
     def __init__(self):
         self.conn = None
         self.container_url = os.getenv('CONTAINER_URL', settings.AZURE["container_url"])