Build OCI images natively from a declarative format
Full Changelog: https://github.com/project-stacker/stacker/compare/v0.20.1...v0.21.0
Full Changelog: https://github.com/project-stacker/stacker/compare/v0.19.1...v0.20.0
Full Changelog: https://github.com/project-stacker/stacker/compare/v0.18.0...v0.19.1