[Install] pytorch_wavelets dependency

[ZhaozhiQIAN]

This is a low priority issue. Fix it only when you have time.

Synthcity now depends on the library pytorch_wavelets. This library cannot be automatically pip installed; instead one has to download it from github and then install it in the directory. This might make it difficult for new users to install.

Is there a possible workaround? If no, we need to update the installation guide.

Also please add PyWavelets to the dependency.