Modify version in build.gradle at a detached commit, and then tag the commit with an annotation.
git checkout --detach master
(Edit: Remove "-SNAPSHOT" in "version" in build.gradle.)
git add build.gradle
git commit -m "Release vX.Y.Z"
git tag -a vX.Y.Z
(Edit: Write a tag annotation in the changelog format.)
See Keep a Changelog for the changelog format. We adopt a part of it for Git's tag annotation like below.
## [X.Y.Z] - YYYY-MM-DD
### Added
- Added a feature.
### Changed
- Changed something.
### Fixed
- Fixed a bug.
Push the annotated tag, then. It triggers a release operation on GitHub Actions after approval.
git push -u origin vX.Y.Z