Update what-input to latest version

Update what-input (https://www.npmjs.com/package/what-input) to the
latest and stable version `v4.0.3`.

Changes:
- No breaking changes between `v2.0.0` and `v4.0.3` for the codebase.
- Update the dist file path.

Outdated dependencies: https://david-dm.org/zurb/foundation-sites