Release action

[kencyke]

• https://github.com/leanprover-community/lean-release-tag
• https://github.com/ncipollo/release-action
• https://github.com/softprops/action-gh-release
• https://docs.github.com/en/repositories/releasing-projects-on-github/automatically-generated-release-notes
• https://github.blog/changelog/2025-08-26-releases-now-support-immutability-in-public-preview/

[kencyke]

Reopen this issue since the release action hasn’t been verified yet.

[kencyke]

OK > https://github.com/kencyke/lean-project/releases/tag/v4.28.0-rc1