Error when training ASR with Transducers on GPU
![image](https://user-images.githubusercontent.com/53433879/188069192-c4997fe2-43fb-4c72-aa8e-a3e6163e07bd.png)

when training ASR with Transducers and leaving 

**freq_masks: 2
time_masks: 10** 

instead of zeroing them out an error occurs

![image](https://user-images.githubusercontent.com/53433879/188069618-69d91380-d074-4054-a610-3ef0f9e378ed.png)
TypeError                                 Traceback (most recent call last)
[<ipython-input-29-1bf927b35c34>](https://localhost:8080/#) in <module>
      1 # Train the model
----> 2 trainer.fit(model)

42 frames
[/usr/local/lib/python3.7/dist-packages/numba/cuda/dispatcher.py](https://localhost:8080/#) in __getitem__(self, args)
    567         if len(args) not in [2, 3, 4]:
    568             raise ValueError('must specify at least the griddim and blockdim')
--> 569         return self.configure(*args)
    570 
    571     def forall(self, ntasks, tpb=0, stream=0, sharedmem=0):

TypeError: unhashable type: 'list'

It happens both in google colab and  when training on local machine.
To reproduce this I skipped  

**config.model.spec_augment.freq_masks = 0
config.model.spec_augment.time_masks = 0**

in colab tutorial **ASR_with_Transducers**

if I zero spec_augment everything works. Could you check if it's a possible bug or it is something I do wrong






