Gemfile in jekyll-diagrams-0.9.1 vs Gemfile in jekyll-diagrams-0.9.2

@@ -1,5 +1,8 @@
+# frozen_string_literal: true
+
 source 'https://rubygems.org'
 
 gemspec
 
-gem 'coveralls', require: false
\ No newline at end of file
+gem 'coveralls', require: false
+gem 'rubocop', require: false