Use default audio resampling type
...instead of relying on the optional librosa dependency `resampy`.

It was only used for `_decode_non_mp3_file_like` anyway and not for the other ones - removing it fixes consistency between decoding methods (except torchaudio decoding)

Therefore I think it is a better solution than adding `resampy` as a dependency in https://github.com/huggingface/datasets/pull/5554

cc @polinaeterna 