Upgrade to Pytorch Lightning 2.0+ and make pip installable

[saveriyo]

(Upgrade from #9)

• Upgrades to Pytorch Lightning 2.0+ and torch 2.0+
• Adds pyproject.toml to be able to run pip install -e . or install direct from github and use the wavtokenizer module
• Adds gitignore
• Adds prepare_libritts.py to download, extract, and prep libritts for training

[erogol]

FYI getting errors in DDP training with your PR. I don't have the logs but it was similar to Lightning-AI/pytorch-lightning#18803

[saveriyo]

Thank you @erogol , I applied a commit to revert to Lightning 2.0.9 which seems to work as suggested in the issue you linked. I also found I needed to set ddp_find_unused_parameters_true with this latest version.