[Security] Bump rack from 1.6.11 to 1.6.12 (#593)
[Security] Bump rack from 1.6.11 to 1.6.12 (#593)

* [Security] Bump rack from 1.6.11 to 1.6.12

Bumps [rack](https://github.com/rack/rack) from 1.6.11 to 1.6.12. **This update includes a security fix.**
- [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/1.6.11...1.6.12)

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

* update changelog for PR #593

Co-authored-by: Jeffery Antoniuk <6a220918cd5608b7dff352c63b11f642708c467a@ualberta.ca>

ualbertalib/avalon,ualbertalib/avalon,ualbertalib/avalon,ualbertalib/avalon