Change black to ruff format on next style release

[echoix]

I've been thinking about this for a while now. I would like to suggest using ruff format . instead of black ..

The idea has already surfaced like in #3319 and some of my comments and discussions a bit everywhere. The problem at the time was that it was difficult (read impossible) to have both tools format exactly the same everywhere, there were slight, known differences.

What's different now, is that considering black's style changes each year, and that we have to adapt, why not skip the next black update and use ruff format as our guideline?

Even though black is fast, and the downloadable version is already mypyc-compiled and thus faster than it was, it still takes just under 30 seconds to run on our repo, without cache. However, ruff format is still way faster, and we already require it in for our contributions. During the holidays, when working on the project, the up to 26-30 seconds per pass where becoming annoying. Anything faster would be a great improvement.

Both projects still follow each other quite closely, I've read PRs in black of ruff maintainers collaborating to stay aligned together.

If you guys agree here, when both tools publish their new 2025 style, I would evaluate one last time the feasibility, and then file a PR for it, including the doc changes.

[echoix]

Ruff published their 2025 style today in ruff 0.9.0. See the blog post here https://astral.sh/blog/ruff-v0.9.0