chore: Set up initial swift package manifest file.

Author: scottmarchant

Package.swift

@@ -0,0 +1,20 @@
+// swift-tools-version: 6.1
+
+import PackageDescription
+
+let package = Package(
+    name: "dispatch-async",
+    products: [
+        .library(
+            name: "DispatchAsync",
+            targets: ["DispatchAsync"]),
+    ],
+    targets: [
+        .target(
+            name: "DispatchAsync"),
+        .testTarget(
+            name: "DispatchAsyncTests",
+            dependencies: ["DispatchAsync"]
+        ),
+    ]
+)