Update files from the datasets library (from 1.6.1)

Release notes: https://github.com/huggingface/datasets/releases/tag/1.6.1

polsum.py

@@ -130,7 +130,7 @@ class Polsum(datasets.GeneratorBasedBuilder):
         ]
 
     def _generate_examples(self, filepaths):
-        """ Yields examples. """
+        """Yields examples."""
         # TODO: This method will receive as arguments the `gen_kwargs` defined in the previous `_split_generators` method.
         # It is in charge of opening the given file and yielding (key, example) tuples from the dataset
         # The key is not important, it's more here for legacy reason (legacy from tfds)