Update Podspec

Author: ricardopereira

WSTagsField.podspec

@@ -10,7 +10,7 @@ Pod::Spec.new do |s|
 
   s.platform = :ios, '9.0'
   s.requires_arc = true
-  s.swift_version = '4.2'
+  s.swift_version = '5.0'
 
   s.source_files = 'WSTagsField/*.{h}', 'Source/**/*.{h,swift}'
   s.frameworks = 'UIKit'