Rakefile in increments-schedule-0.17.0 vs Rakefile in increments-schedule-0.18.0

@@ -1,4 +1,6 @@
+# frozen_string_literal: true
+
 require 'bundler/gem_tasks'
 require 'rspec/core/rake_task'
 require 'rubocop/rake_task'
 
 RSpec::Core::RakeTask.new do |task|