Mac M1 gpu not detected

[garg-aayush]

@vainaixr

The operator 'aten::nonzero' is not currently supported on the MPS backend and will fall back to run on the CPU. This may have performance implications. 
tensor([1.], device='mps:0'

This is a UserWarning. You can ignore it for not. Most likely, some bug in the current nightly version. Don’t worry about it.