Add Swift 5.3 to the Language Version filter
Add Swift 5.3 to the Language Version filter

<https://apple.github.io/swift-evolution/#?version=5.3>

<https://github.com/apple/swift-evolution/pull/1114#issuecomment-582262197>
natecook1000/swift-evolution,abertelrud/swift-evolution,apple/swift-evolution,natecook1000/swift-evolution,abertelrud/swift-evolution,apple/swift-evolution