[Security] Bump rack-cors from 1.0.3 to 1.0.6 (#12395)

Bumps [rack-cors](https://github.com/cyu/rack-cors) from 1.0.3 to 1.0.6. **This update includes a security fix.**
- [Release notes](https://github.com/cyu/rack-cors/releases)
- [Changelog](https://github.com/cyu/rack-cors/blob/master/CHANGELOG.md)
- [Commits](https://github.com/cyu/rack-cors/compare/v1.0.3...v1.0.6

)

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