chore: update minimum app version to iOS 15.

Author: HappyIosDeveloper

Package.swift

@@ -5,7 +5,7 @@ import PackageDescription
 
 let package = Package(
     name: "PersianJustify",
-    platforms: [.iOS(.v13), .macOS(.v11), .tvOS(.v12)],
+    platforms: [.iOS(.v15), .macOS(.v11), .tvOS(.v12)],
     products: [
         // Products define the executables and libraries a package produces, making them visible to other packages.
         .library(