Fix - FLAC ERROR whilst decoding metadata (#1842)

Check this [issue](pytorch/audio#2948)

I encounter this issue by using shard to do training on flacs files...
Notice the issue only occurs when using torchaudio to load a file-like object not a file path.

wenet/dataset/processor.py

@@ -25,6 +25,8 @@
 import torchaudio.compliance.kaldi as kaldi
 from torch.nn.utils.rnn import pad_sequence
 
+torchaudio.utils.sox_utils.set_buffer_size(16500)
+
 AUDIO_FORMAT_SETS = set(['flac', 'mp3', 'm4a', 'ogg', 'opus', 'wav', 'wma'])