fix test

Author: lhoestq

src/datasets/info.py

@@ -339,7 +339,7 @@ def write_to_directory(self, dataset_infos_dir, overwrite=False, pretty_print=Fa
         if os.path.exists(dataset_readme_path):
             dataset_metadata = DatasetMetadata.from_readme(Path(dataset_readme_path))
         else:
-            dataset_metadata = {}
+            dataset_metadata = DatasetMetadata()
         if total_dataset_infos:
             dataset_metadata["dataset_infos"] = [dset_info._to_yaml_dict() for dset_info in total_dataset_infos.values()]
             if len(dataset_metadata["dataset_infos"]) == 1: