Only support sidekiq >= 4.0

Author: dsander

lib/sidekiq-queue-pause.rb

@@ -1,4 +1,8 @@
-require 'celluloid'
+begin
+  require 'celluloid'
+rescue LoadError
+  # Sidekiq 4.2+
+end
 require 'sidekiq'
 require 'sidekiq/fetch'
 

sidekiq-queue-pause.gemspec

@@ -11,5 +11,5 @@ Gem::Specification.new do |s|
   s.require_paths = ['lib']
   s.files         = Dir['lib/**/*rb']
 
-  s.add_dependency 'sidekiq', '~> 3.1'
+  s.add_dependency 'sidekiq', '>= 4.0', '< 5.0'
 end