[Fbsync] Reduce sample rate to avoid test time out (#1640)

Author: mthrok

test/torchaudio_unittest/transforms/batch_consistency_test.py

@@ -189,7 +189,7 @@ def test_batch_spectral_centroid(self):
         self.assertEqual(computed, expected)
 
     def test_batch_pitch_shift(self):
-        sample_rate = 44100
+        sample_rate = 8000
         n_steps = 4
         waveform = common_utils.get_whitenoise(sample_rate=sample_rate)