Guardfile in onebox-1.8.89 vs Guardfile in onebox-1.8.90

@@ -1,4 +1,6 @@
+# frozen_string_literal: true
+
 guard :rspec, cmd: 'bundle exec rspec' do
   watch(%r{^spec/.+_spec\.rb$})
   watch(%r{^lib/(.+)\.rb$})               { |m| "spec/lib/#{m[1]}_spec.rb" }
   watch('spec/spec_helper.rb')            { "spec" }
   watch(%r{^spec/support/(.+)\.rb$})      { "spec" }