chore(deps-dev): bump grunt from 1.4.1 to 1.5.2 (showdownjs#921)

Bumps [grunt](https://github.com/gruntjs/grunt) from 1.4.1 to 1.5.2.
- [Release notes](https://github.com/gruntjs/grunt/releases)
- [Changelog](https://github.com/gruntjs/grunt/blob/main/CHANGELOG)
- [Commits](gruntjs/grunt@v1.4.1...v1.5.2)

---
updated-dependencies:
- dependency-name: grunt
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>