Update Package.swift

Author: swhitty

Package.swift

@@ -5,7 +5,7 @@ import PackageDescription
 let package = Package(
     name: "Mutex",
     platforms: [
- 	   .macOS(.v10_15), .iOS(.v13), .tvOS(.v13), .watchOS(.v6)
+ 	   .macOS(.v10_15), .iOS(.v13), .tvOS(.v13), .watchOS(.v6), .visionOS(.v1)
     ],
     products: [
         .library(