Micha Reiser dc65007fe9 Use rayon to parallelize the stability check ...

<!--
Thank you for contributing to Ruff! To help us out with reviewing, please consider the following:

- Does this pull request include a summary of the change? (See below.)
- Does this pull request include a descriptive title?
- Does this pull request include references to any relevant issues?
-->

## Summary

This PR uses rayon to parallelize the stability check by scheduling each project as its own task.

<!-- What's the purpose of the change? What does it do, and why? -->

## Test Plan

I ran the ecosystem check. It now makes use of all cores (except at the end, there are some large projects). 

## Performance

The check now completes in minutes where it took about 30 minutes before.

<!-- How was it tested? -->

2023-06-30 10:05:25 +02:00

..

src

Use rayon to parallelize the stability check

2023-06-30 10:05:25 +02:00

Cargo.toml

Use rayon to parallelize the stability check

2023-06-30 10:05:25 +02:00