LIBRISPEECH: fix .get_metadata type annotation (#3757)

Author: kuraga

src/torchaudio/datasets/librispeech.py

@@ -118,7 +118,7 @@ def __init__(
 
         self._walker = sorted(str(p.stem) for p in Path(self._path).glob("*/*/*" + self._ext_audio))
 
-    def get_metadata(self, n: int) -> Tuple[Tensor, int, str, int, int, int]:
+    def get_metadata(self, n: int) -> Tuple[str, int, str, int, int, int]:
         """Get metadata for the n-th sample from the dataset. Returns filepath instead of waveform,
         but otherwise returns the same fields as :py:func:`__getitem__`.
 

src/torchaudio/datasets/librispeech_biasing.py

@@ -129,7 +129,7 @@ def __init__(
         self._walker = sorted(str(p.stem) for p in Path(self._path).glob("*/*/*" + self._ext_audio))
         self.blist = blist
 
-    def get_metadata(self, n: int) -> Tuple[Tensor, int, str, int, int, int]:
+    def get_metadata(self, n: int) -> Tuple[str, int, str, int, int, int]:
         """Get metadata for the n-th sample from the dataset. Returns filepath instead of waveform,
         but otherwise returns the same fields as :py:func:`__getitem__`.