Lock minitest-5.15.0 for Ruby 2.2

hsbt · hsbt · commit 5cbc25e6c86b · 2022-07-19T14:31:39.000+09:00
diff --git a/Gemfile b/Gemfile
@@ -4,7 +4,7 @@ gemspec
 
 group :development do
   gem "bundler"
-  gem "minitest"
+  gem "minitest", "5.15.0"
   gem "coveralls"
   gem "rubocop", "~> 1.12.1"
 end
