Rakefile in yao-0.11.3 vs Rakefile in yao-0.12.0

@@ -7,6 +7,7 @@
   #  $ bundle exec rake test TEST=test/test_specified_path.rb
   t.libs.concat ["test"]
   t.test_files = Dir["test/**/test_*.rb"]
   t.verbose = true
   t.ruby_opts = ["-r config"]
+  t.warning = false
 end