Bump handlebars from 4.0.12 to 4.7.8

Bumps [handlebars](https://github.com/handlebars-lang/handlebars.js) from 4.0.12 to 4.7.8.
- [Release notes](https://github.com/handlebars-lang/handlebars.js/releases)
- [Changelog](https://github.com/handlebars-lang/handlebars.js/blob/v4.7.8/release-notes.md)
- [Commits](handlebars-lang/handlebars.js@v4.0.12...v4.7.8)

---
updated-dependencies:
- dependency-name: handlebars
  dependency-type: indirect
...

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

Author: dependabot[bot]