GitLab

- Provide InverseSpectrogram module that corresponds to Spectrogram module
- Add length parameter to the forward method in transforms
Co-authored-by: dgenzel <dgenzel@fb.com>
Co-authored-by: Zhaoheng Ni <zni@fb.com>

ref: D29989551

D30080845

- Renamed torchaudio.functional.create_fb_matrix to torchaudio.functional.melscale_fbanks.
- Added interface with a warning for create_fb_matrix

* Pin MKL to 2021.2.0

Fixes https://github.com/pytorch/pytorch/issues/62424

* Apply the same  constraint for conda builds

Use less-than-equals constraint to avoid dependency conflicts for
python-3.6 environment

Summary:
- Add linear_fbank method
- Add LFCC in transforms