Update CanvasKit.podspec
Update CanvasKit.podspec

add osx deployment target
nlambson/CanvasKit,derrh/CanvasKit,derrh/CanvasKit,derrh/CanvasKit,instructure/CanvasKit,instructure/CanvasKit,instructure/CanvasKit,nlambson/CanvasKit,derrh/CanvasKit,nlambson/CanvasKit,instructure/CanvasKit,nlambson/CanvasKit