turn on strict concurrency

Package.swift

@@ -25,7 +25,7 @@ let package = Package(
         // Targets are the basic building blocks of a package, defining a module or a test suite.
         // Targets can depend on other targets in this package and products from dependencies.
         .target(
-            name: "AblyChat", dependencies: [.product(name: "Ably", package: "ably-cocoa")]),
+            name: "AblyChat", dependencies: [.product(name: "Ably", package: "ably-cocoa")], swiftSettings: [.enableExperimentalFeature("StrictConcurrency")]),
         .testTarget(
             name: "AblyChatTests",
             dependencies: ["AblyChat"])