Upgrade: Bump rack from 1.6.12 to 1.6.13
Upgrade: Bump rack from 1.6.12 to 1.6.13

Bumps [rack](https://github.com/rack/rack) from 1.6.12 to 1.6.13.
- [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/1.6.12...1.6.13)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
helpyio/helpy,scott/helpy__helpdesk_knowledgebase,helpyio/helpy,helpyio/helpy,scott/helpy__helpdesk_knowledgebase,scott/helpy__helpdesk_knowledgebase,helpyio/helpy