Fix issue generating split on Windows

The separator used by `glob.glob` is `os.path.sep`, which is usually `/` but sometimes `\` (Windows). This contribution changes the expected separator from `/` to `os.path.sep` and fixes a bug on Windows where the script fails to generate the train and test splits.

libri_light.py

@@ -147,7 +147,7 @@ class LibriLight(datasets.GeneratorBasedBuilder):
     def _generate_examples(self, archive_path):
         paths = glob.glob(os.path.join(archive_path, self.config.name, "**", "**", "*.flac"))
         for key, path in enumerate(paths):
-            path_split = path.split("/")
+            path_split = path.split(os.path.sep)
             id_ = path_split[-1].replace(".flac", "")
             speaker_id = int(path_split[-3])
             path_json = path.replace(".flac", ".json")