bundle old version of simplecov on old version of Ruby

Author: amatsuda

Gemfile

@@ -8,7 +8,11 @@ gem "rake", ">= 11"
 
 # Use local copy of simplecov in development if you want to
 # gem "simplecov", :path => File.dirname(__FILE__) + "/../simplecov"
-gem "simplecov", git: "https://github.com/simplecov-ruby/simplecov"
+if RUBY_VERSION < "2.5"
+  gem "simplecov", "< 0.19"
+else
+  gem "simplecov", git: "https://github.com/simplecov-ruby/simplecov"
+end
 
 group :test do
   gem "minitest"