fix: use get_s3_client() instead of manual boto3 client creation

flows/backup.py

@@ -12,7 +12,6 @@ from tempfile import TemporaryDirectory
 from prefect import flow, task, get_run_logger
 from prefect.blocks.system import Secret
 from prefect_aws import AwsCredentials
-import boto3
 
 
 @task(name="pg_dump")
@@ -88,12 +87,8 @@ def upload_to_s3(
     """Upload le fichier vers S3 et retourne l'URI."""
     logger = get_run_logger()
     
-    s3_client = boto3.client(
-        "s3",
-        aws_access_key_id=credentials.aws_access_key_id,
-        aws_secret_access_key=credentials.aws_secret_access_key.get_secret_value(),
-        endpoint_url=credentials.aws_endpoint_url,
-    )
+    # Utiliser get_s3_client() qui gère automatiquement l'endpoint
+    s3_client = credentials.get_s3_client()
     
     key = f"{prefix}/{file_path.name}" if prefix else file_path.name