Python o fix

[aiknownc]

Fix for unintended side effect in unfold() assert statement that causes an exception when running with python -O.

Example error:

  File "/home/appuser/miniconda3/envs/jultest/lib/python3.10/site-packages/torch/nn/modules/module.py", line 1750, in _call_impl
    return forward_call(*args, **kwargs)
  File "/home/appuser/miniconda3/envs/jultest/lib/python3.10/site-packages/julius/lowpass.py", line 107, in forward
    out = fft_conv1d(input, self.filters, stride=self.stride)
  File "/home/appuser/miniconda3/envs/jultest/lib/python3.10/site-packages/julius/fftconv.py", line 122, in fft_conv1d
    frames = unfold(input, block_size, fold_stride)
  File "/home/appuser/miniconda3/envs/jultest/lib/python3.10/site-packages/julius/core.py", line 122, in unfold
    return padded.as_strided(shape + [n_frames, kernel_size], strides)
RuntimeError: mismatch in length of strides and shape

[adefossez]

Thanks for the fix! Indeed I never thought of avoiding side effects in assert, probably a best practice to have for the future