Update package versioning

SPM recommends `Package.swift` point to the latest version, but we're
doing the opposite.

Author: stephencelis

Package.swift

@@ -1,4 +1,4 @@
-// swift-tools-version: 5.9
+// swift-tools-version: 6.0
 
 import PackageDescription
 
@@ -25,9 +25,6 @@ let package = Package(
       dependencies: [
         .product(name: "IssueReporting", package: "xctest-dynamic-overlay"),
         .product(name: "XCTestDynamicOverlay", package: "xctest-dynamic-overlay"),
-      ],
-      swiftSettings: [
-        .enableExperimentalFeature("StrictConcurrency")
       ]
     ),
     .testTarget(

[email protected] renamed to [email protected]

@@ -1,4 +1,4 @@
-// swift-tools-version: 6.0
+// swift-tools-version: 5.9
 
 import PackageDescription
 
@@ -25,6 +25,9 @@ let package = Package(
       dependencies: [
         .product(name: "IssueReporting", package: "xctest-dynamic-overlay"),
         .product(name: "XCTestDynamicOverlay", package: "xctest-dynamic-overlay"),
+      ],
+      swiftSettings: [
+        .enableExperimentalFeature("StrictConcurrency")
       ]
     ),
     .testTarget(