Update CI workflow to use Xcode 16.1

GitHub replaced Xcode 16.0 by Xcode 16.2 in macOS-14 images, as per
their support policy.
See actions/runner-images#11203 for details.

.github/workflows/ci.yml

@@ -26,7 +26,7 @@ jobs:
     name: Lint
     runs-on: macos-14
     env:
-      DEVELOPER_DIR: "/Applications/Xcode_16.0.app/Contents/Developer"
+      DEVELOPER_DIR: "/Applications/Xcode_16.1.app/Contents/Developer"
 
     steps:
       - name: Checkout
@@ -60,7 +60,7 @@ jobs:
             xcode: '15.3'    # Swift 5.10
             ios-simulator: 'iPhone 15 Pro'
           - macos: 14
-            xcode: '16.0'    # Swift 6.0
+            xcode: '16.1'    # Swift 6.0
             ios-simulator: 'iPhone 16 Pro'
 
     steps: