Bump rack from 1.6.5 to 1.6.11
Bump rack from 1.6.5 to 1.6.11

Bumps [rack](https://github.com/rack/rack) from 1.6.5 to 1.6.11.
- [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/1.6.5...1.6.11)
taise/Spectrometer,taise/Spectrometer