Replace resampy with pysox for audio resampling

[justinsalamon]

Turns out resampy is SLOW. We could speed openl3 quite a bit by swapping it out with pysox, resample the audio into a tempfile and load the templfile for further processing.

with tempfile.TemporaryDirectory() as tempdir:
    filename48 = os.path.join(tempdir, os.path.basename(os.path.splitext(file_path)[0]) + "_48.wav") 
    # resample to 48000 Hz
    tfm = sox.Transformer()
    tfm.convert(samplerate= 48000, n_channels=1)
    tfm.build(file_path, filename48)

    # load the audio file
    sr = 48000
    audio, srload = librosa.load(filename48, sr=None)
    assert srload == sr

NOTE: this example assumes wav input, and would have to be adapted to support various formats (in particular mp3)