build(deps-dev): bump @types/shelljs from 0.8.12 to 0.8.15

Bumps [@types/shelljs](https://github.com/DefinitelyTyped/DefinitelyTyped/tree/HEAD/types/shelljs) from 0.8.12 to 0.8.15.
- [Release notes](https://github.com/DefinitelyTyped/DefinitelyTyped/releases)
- [Commits](https://github.com/DefinitelyTyped/DefinitelyTyped/commits/HEAD/types/shelljs)

---
updated-dependencies:
- dependency-name: "@types/shelljs"
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>