SIENTIAPDE-1231

Refactor tests and update model_repository.py for clarity and consistency

- Added a blank line in model_repository.py for improved readability.
- Adjusted formatting in test_mlflow.py to streamline assertions.
- Updated ensure_bucket_exists method tests in test_minio_repository.py to reflect the new return value of None instead of True.

tests/laborious/activities/test_mlflow.py

@@ -200,9 +200,7 @@ async def test_request_predict(mock_max, mock_to_datetime, mock_dataframe, mlflo
     mock_to_datetime.assert_called_once_with(
         mock_dataframe.return_value.__getitem__.return_value, format=DATETIME_FORMAT_WITH_TZ
     )
-    mock_to_datetime.return_value.dt.strftime.assert_called_once_with(
-        DATETIME_FORMAT
-    )
+    mock_to_datetime.return_value.dt.strftime.assert_called_once_with(DATETIME_FORMAT)
 
     mock_to_datetime.assert_called_once_with(
         mock_dataframe.return_value.__getitem__.return_value, format=DATETIME_FORMAT_WITH_TZ