Gemfile in key_tree-0.5.3 vs Gemfile in key_tree-0.6.0

@@ -1,4 +1,6 @@
+# frozen_string_literal: true
+
 source 'https://rubygems.org'
 
 git_source(:github) { |repo_name| "https://github.com/#{repo_name}" }
 
 begin