Enabled upcoming language features across targets in the Package file.

Package.swift

@@ -2,6 +2,13 @@
 
 import PackageDescription
 
+// Upcoming language features adopted ahead of the next language mode.
+let swiftSettings: [SwiftSetting] = [
+    .enableUpcomingFeature("ExistentialAny"),
+    .enableUpcomingFeature("InternalImportsByDefault"),
+    .enableUpcomingFeature("MemberImportVisibility"),
+]
+
 let package = Package(
     name: "playdate-kit",
     products: [
@@ -29,17 +36,13 @@ let package = Package(
             name: "PlaydateKit",
             dependencies: ["CPlaydate"],
             path: "Sources/PlaydateKit",
-            swiftSettings: [
+            swiftSettings: swiftSettings,
-                .enableUpcomingFeature("ApproachableConcurrency"),
-            ],
         ),
         .testTarget(
             name: "PlaydateKitTests",
             dependencies: ["PlaydateKit"],
             path: "Tests/PlaydateKit",
-            swiftSettings: [
+            swiftSettings: swiftSettings,
-                .enableUpcomingFeature("ApproachableConcurrency"),
-            ],
         ),
     ]
 )