Bug/319 Package.swift update to v9 (ninjaprox#321)

* ninjaprox#319: Bump IPHONEOS_DEPLOYMENT_TARGET = 8.0 -> 9.0

* ninjaprox#319: Updated Package.swift to v9

Co-authored-by: Vinh Nguyen <ninjaprox@gmail.com>

Author: Tim Walsh

Package.swift

@@ -6,7 +6,7 @@ import PackageDescription
 let package = Package(
     name: "NVActivityIndicatorView",
     platforms: [
-        .iOS(.v8),
+        .iOS(.v9),
         .tvOS(.v9)
     ],
     products: [