added platforms to fix issue in Xcode archiving process (#3)

Author: MohSalahNassar

Package.swift

@@ -5,6 +5,11 @@ import PackageDescription
 
 let package = Package(
     name: "FloatingLabelTextFieldSwiftUI",
+    platforms: [
+        .iOS(.v13),
+        .macOS(.v10_15),
+        .tvOS(.v13)
+    ],
     products: [
         // Products define the executables and libraries produced by a package, and make them visible to other packages.
         .library(