Use Poetry for package management

[Aceticia]

With this issue looking like about to close, would it be a good idea to switch to poetry for dependency management & package installing? I'm still experimenting how well poetry works with torch and cuda, but if it does work I see it as a nice upgrade from requirements.txt.

This provides a few advantages:

1. All dependencies can be specified together with certain other python package options in pyproject.toml
2. Dev dependencies and normal dependencies can be more easily separated
3. Automatically generated lock files are more reliable for reproducibility compared to requirements.txt
4. Adding dependencies to an existing environment is easier

[cs-mshah]

I support this.