Update minitest requirement from ~> 5.11 to ~> 6.0 (#214)

Updates the requirements on [minitest](https://github.com/minitest/minitest) to permit the latest version.
- [Changelog](https://github.com/minitest/minitest/blob/master/History.rdoc)
- [Commits](minitest/minitest@v5.11.0...v6.0.1)

---
updated-dependencies:
- dependency-name: minitest
  dependency-version: 6.0.1
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

Gemfile

@@ -4,7 +4,7 @@ source "https://rubygems.org"
 gemspec
 
 gem "irb"
-gem "minitest", "~> 5.11"
+gem "minitest", "~> 6.0"
 gem "minitest-rg", "~> 5.3"
 gem "rake", "~> 13.0"
 gem "rubocop", "1.82.1"