Update minitest requirement from ~> 4.0 to ~> 5.12
Update minitest requirement from ~> 4.0 to ~> 5.12

Updates the requirements on [minitest](https://github.com/seattlerb/minitest) to permit the latest version.
- [Release notes](https://github.com/seattlerb/minitest/releases)
- [Changelog](https://github.com/seattlerb/minitest/blob/master/History.rdoc)
- [Commits](https://github.com/seattlerb/minitest/compare/v4.0.0...v5.12.0)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>
Narnach/torm