Use rubocop-git from dev branch

Author: blelump

Gemfile

@@ -5,7 +5,7 @@ git_source(:github) { |name| "https://github.com/#{name}.git" }
 group :development, :test do
   gem 'ast'
   gem 'rubocop', '0.49'
-  gem 'rubocop-git', github: 'blelump/rubocop-git'
+  gem 'rubocop-git', github: 'blelump/rubocop-git', branch: 'dev'
 end
 
 gemspec