message: Update docstring for compression_type argument of TextLineDataset.
  compression_type will accept a scalar String tensor, not just a Python string.
diff: @@ -1943,8 +1943,8 @@ class TextLineDataset(Dataset):
  Args:
  filenames: A `tf.string` tensor containing one or more filenames.
  - compression_type: A string, one of: `""` (no compression), `"ZLIB"`, or
  - `"GZIP"`.
  + compression_type: A `tf.string` scalar evaluating to one of `""` (no
  + compression), `"ZLIB"`, or `"GZIP"`.
  """
  super(TextLineDataset, self).__init__()
  self._filenames = ops.convert_to_tensor(
  