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"])

rag/utils/azure_spn_conn.py

@@ -24,7 +24,7 @@ from azure.storage.filedatalake import FileSystemClient
 
 
 @singleton
-class RAGFlowAzureSpnBlob(object):
+class RAGFlowAzureSpnBlob:
     def __init__(self):
         self.conn = None
         self.account_url = os.getenv('ACCOUNT_URL', settings.AZURE["account_url"])

rag/utils/minio_conn.py

@@ -24,7 +24,7 @@ from rag.utils import singleton
 
 
 @singleton
-class RAGFlowMinio(object):
+class RAGFlowMinio:
     def __init__(self):
         self.conn = None
         self.__open__()

rag/utils/oss_conn.py

@@ -24,7 +24,7 @@ from rag import settings
 
 
 @singleton
-class RAGFlowOSS(object):
+class RAGFlowOSS:
     def __init__(self):
         self.conn = None
         self.oss_config = settings.OSS

rag/utils/s3_conn.py

@@ -23,7 +23,7 @@ from rag.utils import singleton
 from rag import settings
 
 @singleton
-class RAGFlowS3(object):
+class RAGFlowS3:
     def __init__(self):
         self.conn = None
         self.s3_config = settings.S3