Set version 3.2.1

Author: ishkawa

APIKit.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name     = "APIKit"
-  s.version  = "3.1.2"
+  s.version  = "3.2.1"
   s.summary  = "Type-safe networking abstraction layer that associates request type with response type."
   s.homepage = "https://github.com/ishkawa/APIKit"