Update podspec

TrueTime.podspec

@@ -1,12 +1,13 @@
 Pod::Spec.new do |s|
   s.name = 'TrueTime'
-  s.version = '5.0.1'
+  s.version = '5.0.2'
   s.summary = 'NTP library for Swift. Get the true time impervious to device clock changes.'
 
   s.homepage = 'https://github.com/instacart/TrueTime.swift'
   s.license = { :type => 'Apache License, Version 2.0', :file => 'LICENSE' }
   s.author = { 'Michael Sanders' => '[email protected]' }
   s.source = { :git => 'https://github.com/instacart/TrueTime.swift.git', :tag => s.version }
+  s.swift_version = '5.0'
 
   s.requires_arc = true
   s.ios.deployment_target = '8.0'