Update copyright year in new test file

Author: gmedori

Tests/TestingTests/Test.TraitTests.swift

@@ -1,7 +1,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2023 Apple Inc. and the Swift project authors
+// Copyright (c) 2026 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information