Update README

Package@swift-4.0.swift

@@ -1,7 +1,7 @@
 // swift-tools-version:4.0
 import PackageDescription
 
-#if os(macOS) || os(iOS) || os(watchOS) || os(tvOS) || os(xrOS)
+#if os(macOS) || os(iOS) || os(watchOS) || os(tvOS) || os(visionOS)
 let dependencies: [Package.Dependency] = []
 #else
 let dependencies: [Package.Dependency] = [.package(url: "https://github.com/IBM-Swift/CZlib.git", .exact("0.1.2"))]

README.md

@@ -3,7 +3,7 @@
 [![Swift Package Manager compatible](https://img.shields.io/badge/SPM-compatible-brightgreen.svg)](https://github.com/apple/swift-package-manager)
 [![Carthage compatible](https://img.shields.io/badge/Carthage-compatible-4BC51D.svg?style=flat)](https://github.com/Carthage/Carthage)
 [![CocoaPods Compatible](https://img.shields.io/cocoapods/v/ZIPFoundation.svg)](https://cocoapods.org/pods/ZIPFoundation)
-[![Platform](https://img.shields.io/badge/Platforms-macOS%20|%20iOS%20|%20tvOS%20|%20watchOS%20|%20Linux-lightgrey.svg)](https://github.com/weichsel/ZIPFoundation)
+[![Platform](https://img.shields.io/badge/Platforms-macOS%20|%20iOS%20|%20tvOS%20|%20watchOS%20|%20visionOS%20|%20Linux-lightgrey.svg)](https://github.com/weichsel/ZIPFoundation)
 [![Twitter](https://img.shields.io/badge/twitter-@weichsel-blue.svg?style=flat)](http://twitter.com/weichsel)
 
 ZIP Foundation is a library to create, read and modify ZIP archive files.  
@@ -40,7 +40,7 @@ To learn more about the performance characteristics of the framework, you can re
 
 ## Requirements
 
-- iOS 12.0+ / macOS 10.11+ / tvOS 12.0+ / watchOS 2.0+
+- iOS 12.0+ / macOS 10.11+ / tvOS 12.0+ / watchOS 2.0+ / visionOS 1.0+
 - Or Linux with zlib development package
 - Xcode 11.0
 - Swift 4.0