Use swiftlang repo for SwingSyntax

Author: emorydunn

Package.swift

@@ -18,7 +18,7 @@ var package = Package(
 		.package(url: "https://github.com/apple/swift-argument-parser.git", from: "1.5.0"),
 
 		// Depend on the latest Swift 5.9 prerelease of SwiftSyntax
-		.package(url: "https://github.com/apple/swift-syntax.git", from: "600.0.0"),
+		.package(url: "https://github.com/swiftlang/swift-syntax.git", "509.0.0"..<"602.0.0"),
 
 		// Documentation
 		.package(url: "https://github.com/apple/swift-docc-plugin", from: "1.0.0"),