add tvos to podspec

CryptoSwift.podspec

@@ -14,6 +14,8 @@ Pod::Spec.new do |s|
   s.osx.deployment_target = "10.9"
   s.watchos.platform = :watchos, '2.0'
   s.watchos.deployment_target = "2.0"
+  s.tvos.platform = :tvos, '9.0'
+  s.tvos.deployment_target = "9.0"
   s.source_files  = "CryptoSwift/**/*.swift"
   s.requires_arc = true
 end