CI: Cirrus CI will shut down effective Monday, June 1, 2026

[zaikunzhang]

See https://cirruslabs.org/ and https://github.com/search?q=Cirrus+CI&type=issues .

All Cirrcus-based CI should be migrated to GitHub Actions or removed. This includes at least

• https://github.com/libprima/prima/blob/main/.cirrus.yml

[zaikunzhang]

See here for related discussions

https://github.com/search?q=Cirrus+CI&type=issues

especially,

scipy/scipy#24990