Rakefile in doing-2.0.11 vs Rakefile in doing-2.0.13

@@ -4,9 +4,11 @@
 require 'rdoc'
 require 'rdoc/task'
 require 'rake/testtask'
 require 'open3'
 require 'yard'
+require 'parallel_tests'
+require 'parallel_tests/tasks'
 
 YARD::Rake::YardocTask.new do |t|
  t.files = ['lib/doing/*.rb']
  t.options = ['--markup-provider=redcarpet', '--markup=markdown', '--no-private', '-p', 'yard_templates']
  # t.stats_options = ['--list-undoc']