corepc workflow notes

Because there are so many integration test jobs (one for each version of Core supported) we cannot stay under the 20 job limit.

ref: https://docs.github.com/en/actions/learn-github-actions/usage-limits-billing-and-administration

The minimal/recent lock files are handled by CI (rust.yml).

Jobs

Run from rust.yml unless stated otherwise. Total 11 jobs.

0. Prepare
1. Stable - minimal
2. Stable - recent
3. Nightly - minimal
4. Nightly - recent
5. MSRV - minimal
6. MSRV - recent
7. Lint
8. Docs
9. Docsrs
10. Format
11. Verify

+15 jobs - 1 for each supported version of Core.