Labwork on ASR

[jeremyfix]

That would be great to :

• check that the correct lenghts have been provided to the pack padded sequence in the Waveform processor ; This could be checked in the first unit test of the test_implementation script ; we check for the size of the tensors, the values of the tensor , but the user could have kept the default "lengths" for pack padded which may consider all the seuqences have the maximal length and not their real lenghts; This can forgiven silently !
• check for the functionning of the conda venv ; we got a permission denied today once the students copied the provided archive and tried to source it !