Consider switching to pyproject.toml

[NeilGirdhar]

When doing an editable install of jaxopt, I get:

DEPRECATION: Config settings are ignored for project file:///Users/neil/src/jaxopt. pip 24.0 will enforce this behaviour change. A possible replacement is to use --use-pep517 or add a pyproject.toml file to the project.

JaxOpt has a fairly simple setup.py, so it would be quite easy to convert it to a pyproject.toml. This has other benefits like pulling pylint's settings into the common file (like the Jax team did). Would such a PR be welcome?