fix: undefined method silence_warnings' for main:Object

this errors raises in gem resque-reports, if use activesupport
version 3.1.12

But silence_warnings not suspend warnings about `Resque::Helpers` because
resque reports not use warnigns, and this warn still present if use silence_warnings

lib/resque/integration/unique.rb

@@ -5,7 +5,7 @@
 require 'active_support/core_ext/module/aliasing'
 
 require 'resque/plugins/lock'
-silence_warnings { require 'resque/plugins/progress' } # suppress Resque::Helpers warn
+require 'resque/plugins/progress'
 
 module Resque
   module Integration