Bump to 4.5.20

Author: bensmiley

ChatSDK.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = "ChatSDK"
-  s.version          = "4.5.19"
+  s.version          = "4.5.20"
   s.summary          = "Chat SDK - Mobile messaging framework for iOS"
   s.homepage         = "http://chatsdk.co"
   s.license          = { :type => 'Chat SDK License', :file => 'LICENSE.md' }