Bump apps/on_ruby from `e9e1a72` to `b4c9791`
Bump apps/on_ruby from `e9e1a72` to `b4c9791`

Bumps [apps/on_ruby](https://github.com/phoet/on_ruby) from `e9e1a72` to `b4c9791`.
- [Release notes](https://github.com/phoet/on_ruby/releases)
- [Commits](https://github.com/phoet/on_ruby/compare/e9e1a72f93fd0297ca54e3b2cc3114202f0a12a8...b4c9791729cdf1668871ebf671bf8accb712918e)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
eliotsykes/real-world-rails