Dont specify the Swift version in the podspec.

Author: Luc Dion

PinLayout.podspec

@@ -16,7 +16,6 @@ Pod::Spec.new do |spec|
   spec.author        = { "Luc Dion" => "[email protected]" }
   spec.source        = { :git => "https://github.com/layoutBox/PinLayout.git", :tag => "#{spec.version}" }
   spec.source_files  = "Sources/**/*.swift"
-  #spec.swift_version = '4.1'
 
   spec.ios.deployment_target  = '8.0'
   spec.ios.frameworks         = 'Foundation', 'CoreGraphics', 'UIKit'