message: Fix iterator_test
diff: @@ -946,7 +946,9 @@ class IteratorTest(test_base.DatasetTestBase, parameterized.TestCase):
  @def_function.function
  def fn():
  - dataset = dataset_ops._GeneratorDataset(1, init_fn, next_fn, finalize_fn)
  + output_spec = tensor_spec.TensorSpec((), dtypes.int64)
  + dataset = dataset_ops._GeneratorDataset(1, init_fn, next_fn, finalize_fn,
  + output_spec)
  iterator = iter(dataset)
  next(iterator)
  