Spectrodataset link rework

[Gautzilla]

I reworked the SpectroDataset.link_audio_dataset() method so that it now works if the AudioDataset contains more data than the SpectroDataset (providing all SpectroData of the sds can still be effectively linked to an AudioData of the ads):

ads = AudioDataset(...)
ads2 = AudioDataset(...) # Same parameters as ads
ads2.data = [ad for ad in ads2.data[:-1] # But shorter than ads

sds = SpectroDataset.from_audio_dataset(
    audio_dataset=ads2,
    ...
)

sds.link_audio_dataset(audio_dataset=ads)

This last line raised an exception before as len(ads.data] != len(sds.data).

With this PR, the link will be done effectively as long as all spectro data have corresponding audio data in the ads to be linked.

Related issue

This PR resolves #333