Explicit platform versions - as low as it can be

Author: mattmassicotte

Package.swift

@@ -4,6 +4,13 @@ import PackageDescription
 
 let package = Package(
 	name: "Rearrange",
+	platforms: [
+		.macOS(.v10_13),
+		.iOS(.v11),
+		.tvOS(.v11),
+		.watchOS(.v5),
+		.macCatalyst(.v13),
+	],
 	products: [
 		.library(name: "Rearrange", targets: ["Rearrange"]),
 	],