Update minitest

Author: monkstone

jruby_art.gemspec

@@ -37,8 +37,8 @@ Gem::Specification.new do |spec|
   spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
   spec.require_paths = ['lib']
   spec.required_ruby_version = '>= 2.5'
-  spec.add_development_dependency 'minitest', '~> 5.10'
-  spec.add_runtime_dependency 'rake', '~> 12.3'
+  spec.add_development_dependency 'minitest', '~> 5.15'
+  spec.add_runtime_dependency 'rake', '~> 13.0'
   spec.requirements << 'A decent graphics card'
   spec.requirements << 'java runtime >= 11.0.3+'
 end