Results 3 issues of Roman Makarov

Solves issue #20. Hard-coded value of input channels (num_mels) is replaced by a parameter from config. https://github.com/rmakarovv/iSTFTNet-pytorch/blob/385dda161b011dd68313c83d917923acdafa073a/models.py#L81

Hard-coded number of input channels (80) can be replaced with `h.num_mels`. https://github.com/rishikksh20/iSTFTNet-pytorch/blob/ecbf0f635b36432bd3e432790326591bc86cadbc/models.py#L81

**Describe the bug** When I run speed generation benchmark I get the following message: > INFO - You passed a model that is compatible with the Marlin int4*fp16 GPTQ kernel...

bug