chore(release): 18.0.3 [skip ci]

## [18.0.3](https://github.com/markedjs/marked/compare/v18.0.2...v18.0.3) (2026-05-01)

### Bug Fixes

* avoid task checkbox for setext heading text ([#3960](https://github.com/markedjs/marked/issues/3960)) ([2608e81](https://github.com/markedjs/marked/commit/2608e810c037a4d796dc31a8a16bc78ca0178b6d))