gem: adds rubocop performance

Gemfile.lock

@@ -107,6 +107,8 @@ GEM
       rainbow (>= 2.2.2, < 4.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (>= 1.4.0, < 1.7)
+    rubocop-performance (1.5.0)
+      rubocop (>= 0.71.0)
     rubocop-rspec (1.36.0)
       rubocop (>= 0.68.1)
     ruby-progressbar (1.10.1)
@@ -128,6 +130,7 @@ DEPENDENCIES
   pry-byebug
   rating!
   rspec-rails
+  rubocop-performance
   rubocop-rspec
   shoulda-matchers
 

rating.gemspec

@@ -26,6 +26,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'mysql2'
   spec.add_development_dependency 'pry-byebug'
   spec.add_development_dependency 'rspec-rails'
+  spec.add_development_dependency 'rubocop-performance'
   spec.add_development_dependency 'rubocop-rspec'
   spec.add_development_dependency 'shoulda-matchers'
 end