Update smoke test (#2455)

Summary:
Import StreamReader from the new location

Pull Request resolved: https://github.com/pytorch/audio/pull/2455

Reviewed By: nateanl

Differential Revision: D36959668

Pulled By: mthrok

fbshipit-source-id: c2b8c9f9dff1ec306ea39c495294faa9208b3c4e

test/smoke_test/smoke_test.py

@@ -9,4 +9,4 @@ import torchaudio.pipelines  # noqa: F401
 import torchaudio.sox_effects  # noqa: F401
 import torchaudio.transforms  # noqa: F401
 import torchaudio.utils  # noqa: F401
-from torchaudio.prototype.io import Streamer  # noqa: F401
+from torchaudio.io import StreamReader  # noqa: F401