test/test_tsort.rb: Specify frozen_string_literal: true.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@52574 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
2015-11-14 09:43:18 +00:00 · 2015-11-14 09:43:18 +00:00 · af4c1ac8af
--- a/test/test_tsort.rb
+++ b/test/test_tsort.rb
@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'tsort'
 require 'test/unit'