Set xcode version to 16.4 in macos runner

Author: Recouse

.github/workflows/ci.yml

@@ -21,6 +21,8 @@ jobs:
     steps:
     - name: Checkout
       uses: actions/checkout@v4
+    - name: Set Xcode version
+      run: sudo xcode-select -s /Applications/Xcode_16.4.0.app
     - name: Build
       run: swift build -v
     # - name: Run tests