Consider replacing hatch with pixi

[stevemessick]

Overview of package managers:
https://dublog.net/blog/so-many-python-package-managers/

pixi:
https://github.com/prefix-dev/pixi

It is not yet GA, so we might want to wait until it is.

[stevemessick]

While considering it, also remember hatch is used by kagglehub and possibly others. It's probably best to maintain consistency, so this may be a bigger job than we thought.