add swift version to podspec

Jan Bednář · Jan Bednář · commit ca89d9dacba2 · 2018-10-03T20:54:05.000+02:00
diff --git a/SwiftyTimer.podspec b/SwiftyTimer.podspec
@@ -14,4 +14,6 @@ Pod::Spec.new do |s|
   s.watchos.deployment_target = '2.0'
 
   s.source_files = 'Sources/*.swift'
+
+  s.swift_version = '3.0'
 end
