Audio dir stats formats - breaks on mp3

[turian]

Python soundfile cannot read mp3s but this is one of the formats that is searched for by audio_dir_stats_wav: https://github.com/neuralaudio/hear-eval-kit/blob/531adcc778582300fcdf7f4a19507cb16b8d31aa/heareval/tasks/util/audio.py#L93

Update the formats that are searched for or use something like audioread in the case of an mp3. Perhaps include the soundfile info function in a try block and load in with audioread and get the stats that way if it fails.