Using MMS model with star token for batch size > 1

[huangruizhe]

The current implementation assumes batch size is one, when attaching the star dimension:

audio/src/torchaudio/pipelines/_wav2vec2/utils.py

Line 41 in ea437b3

star_dim = torch.zeros((1, output.size(1), 1), dtype=output.dtype, device=output.device)

However, the underlying Wav2vec model supports batch size greater than one. So this line should instead be:

star_dim = torch.zeros((output.size(0), output.size(1), 1), dtype=output.dtype, device=output.device)