fixup! Avoid using minitest 5.12.0

Author: pirj

Gemfile

@@ -27,8 +27,10 @@ if RUBY_VERSION >= '1.9.3'
   end
 end
 
+# Minitest version 5.12.0 rely on Ruby 2.4 features and doesn't specify a Ruby version constraint
+gem 'minitest', '!= 5.12.0'
+
 gem 'mime-types'
-gem 'minitest'
 gem 'nokogiri'
 gem 'rake'
 gem 'rack-cache'