use pixi

[bollwyvl]

Elevator Pitch

migrate doit workflows to pixi.

Motivation

with perhaps only a little toml manipulation, pixi will handle the relatively complex test matrix... though starting off, may drastically reduce to oldest and latest excursions, with even those being a lot tighter.

we'll lose some native parallel execution, but can likely paper over that if needed.

Design Ideas

• https://github.com/jupyrdf/ipyelk/blob/master/pixi.toml
• https://github.com/deathbeds/urljsf/blob/main/pixi.toml