Add stft_n_filters to BaseDCUNet

[JorisCos]

This PR adds stft_n_filters as mentionned in #404.
It also fixes the defaults parameter of DCUNet to match its paper as mentionned in #400

[mpariente]

There is a problem with CI (1.7.0 build) that might be related to the stride (changed input shape), could someone have a look?

The other STOI problem on the nightly build should be fixed now.

[JorisCos]

We can have a closer look to what's wrong with DCCRNet @jonashaag

[mpariente]

Could you explain the fix please? What was wrong?

[JorisCos]

Sure, I added stft_n_filters in DCUNet and DCCRNet. I also changed the default values of stft_n_filters stft_n_kernel_size and stft_stride. In the tests the models are initialized with the default values and the tests use hard-coded values tied to those default parameters, so they needed to be changed.

[JorisCos]

At first, I was confused by the jit tests on DCCRNet that kept failing, but it was because I didn't change this line
masknet_kwargs.setdefault("n_freqs", stft_n_filters // 2) .

[JorisCos]

Before, because stft_n_filters was equal to stft_kernel_size masknet_kwargs.setdefault("n_freqs", stft_kernel_size // 2) was ok but it had to be changed

[mpariente]

Makes complete sense, thanks for the explanation!

[mpariente]

After the required edits on the tests, we'll merge that, thanks again

[mpariente]

Thanks again !