Update minitest requirement from ~> 5.21 to ~> 6.0 (#86)

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@v5.27.0...v6.0.0)

---
updated-dependencies:
- dependency-name: minitest
  dependency-version: 6.0.0
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

Gemfile.lock

@@ -7,7 +7,9 @@ PATH
 GEM
   remote: https://rubygems.org/
   specs:
-    minitest (5.27.0)
+    minitest (6.0.0)
+      prism (~> 1.5)
+    prism (1.7.0)
     rake (13.3.1)
     rake-compiler (1.3.1)
       rake
@@ -20,7 +22,7 @@ PLATFORMS
   ruby
 
 DEPENDENCIES
-  minitest (~> 5.21)
+  minitest (~> 6.0)
   rake (~> 13.0)
   rake-compiler (~> 1.3)
   ruby_native_statistics!

ruby_native_statistics.gemspec

@@ -37,7 +37,7 @@ Gem::Specification.new do |spec|
 
   spec.add_development_dependency 'rake-compiler', '~> 1.3'
   spec.add_development_dependency "rake", "~> 13.0"
-  spec.add_development_dependency 'minitest', '~> 5.21'
+  spec.add_development_dependency 'minitest', '~> 6.0'
 
   spec.version = RubyNativeStatistics::VERSION
 end