Update README.md

Author: swhitty

README.md

@@ -11,7 +11,7 @@ Macros for [FlyingFox](https://github.com/swhitty/FlyingFox) allowing handlers t
 
 FlyingFoxMacros can be installed by using Swift Package Manager.
 
-**Note:** FlyingFox requires Swift 5.9 on Xcode 15+. It runs on iOS 13+, tvOS 13+, watchOS 8+, macOS 10.15+ and Linux. Windows 10 support is experimental.
+**Note:** FlyingFoxMacros requires Swift 6.1 on Xcode 16.4+. It runs on iOS 13+, tvOS 13+, watchOS 8+, macOS 10.15+ and Linux. Windows 10 support is experimental.
 
 To install using Swift Package Manager, add this to the `dependencies:` section in your Package.swift file: