Update podspec

Author: tinder-cfuller

StateMachine.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name     = 'StateMachine'
-  s.version  = '0.3.0'
+  s.version  = '0.4.0'
   s.summary  = 'A state machine library in Swift'
   s.homepage = 'https://github.com/Tinder/StateMachine'
   s.license  = { :type => 'BSD 3-Clause "New" or "Revised" License', :file => 'LICENSE' }