Remove rubocop for all Ruby versions

Author: JuanVqz

Rakefile

@@ -12,12 +12,10 @@ Rake::TestTask.new do |task|
   task.pattern = "test/**/*_test.rb"
 end
 
-RuboCop::RakeTask.new
-
 Reek::Rake::Task.new
 
 RubyCritic::RakeTask.new do |task|
   task.paths = FileList["lib/**/*.rb"]
 end
 
-task default: %i[test reek rubocop]
+task default: %i[test reek]