chart.rb in write_xlsx-1.10.0

- old
+ new

@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
+# frozen_string_literal: true
 
 require 'write_xlsx/package/xml_writer_simple'
 require 'write_xlsx/gradient'
 require 'write_xlsx/chart/legend'
 require 'write_xlsx/utility'