Gemfile in mojo_magick-0.6.7 vs Gemfile in mojo_magick-0.6.8

@@ -1,8 +1,15 @@
 source "https://rubygems.org"
 
 group :test, :development do
   gem "irb", require: false
   gem "simplecov", require: false
+
+  gem "bundle-audit"
+  gem "bundler"
+  gem "minitest"
+  gem "rake"
+  gem "rubocop"
+  gem "rubocop-performance"
 end
 
 gemspec