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/utils/repository/test_minio_repository.py

@@ -67,7 +67,7 @@ def test_close(minio_repository):
 
 
 def test_ensure_bucket_exists_bucket_exists(minio_repository):
-    assert minio_repository.ensure_bucket_exists({}) is True
+    assert minio_repository.ensure_bucket_exists({}) is None
 
     minio_repository.s3_client.head_bucket.assert_called_once_with(Bucket='test')
 
@@ -77,7 +77,7 @@ def test_ensure_bucket_exists_bucket_not_exists_create_success(minio_repository)
         error_response={'Error': {'Code': '404'}}, operation_name='head_bucket'
     )
 
-    assert minio_repository.ensure_bucket_exists({}) is True
+    assert minio_repository.ensure_bucket_exists({}) is None
 
     minio_repository.s3_client.head_bucket.assert_called_once_with(Bucket='test')
     minio_repository.s3_client.create_bucket.assert_called_once_with(Bucket='test')