Bump handlebars from 4.0.12 to 4.5.1 in /example

Bumps [handlebars](https://github.com/wycats/handlebars.js) from 4.0.12 to 4.5.1.
- [Release notes](https://github.com/wycats/handlebars.js/releases)
- [Changelog](https://github.com/wycats/handlebars.js/blob/v4.5.1/release-notes.md)
- [Commits](handlebars-lang/handlebars.js@v4.0.12...v4.5.1)

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

Author: dependabot[bot]