Use uv for project management

[cboulay]

We should probably upgrade from setup.py to pyproject.toml.

I've been using uv to manage all my Python projects recently and I like it much more than poetry.

I will put together a PR to migrate to using uv, including refactoring some folders and CI scripts.

[cbrnr]

Same, just note that uv resolves differently than pip, which might sometimes be a problem (see discussion in e.g. MIT-LCP/wfdb-python#511).

In any case, migrating to pyproject.toml is the default nowadays, which we should do no matter what.