GHA: Set Xcode version to 16.0

... old one not supported anymore.

Author: helje5

.github/workflows/swift.yml

@@ -31,7 +31,7 @@ jobs:
       - name: Select latest available Xcode
         uses: maxim-lobanov/[email protected]
         with:
-          xcode-version: 13.2.1
+          xcode-version: 16.0.0
       - name: Checkout Repository
         uses: actions/checkout@v3
       - name: Build Swift Debug Package