Bump rack from 2.0.6 to 2.2.3
Bumps [rack](https://github.com/rack/rack) from 2.0.6 to 2.2.3.
- [Release notes](https://github.com/rack/rack/releases)
- [Changelog](https://github.com/rack/rack/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rack/rack/compare/2.0.6...2.2.3)
Signed-off-by: dependabot[bot] <support@github.com>