updated podspect

Author: natemann

StaticTableViewDatasource.podspec

@@ -9,6 +9,7 @@ Pod::Spec.new do |s|
 
   s.name         = "StaticTableViewDatasource"
   s.version      = "1.2.0"
+  swift_version  = "4.2"
   s.summary      = "Create static table views in a declarative style"
   # s.description  = <<-DESC
   #                  DESC