Rakefile in oxr-0.5.0 vs Rakefile in oxr-0.6.0

@@ -1,4 +1,6 @@
+# frozen_string_literal: true
+
 require 'bundler/gem_tasks'
 require 'rake/testtask'
 
 Rake::TestTask.new(:test) do |t|
   t.libs << 'test'