Pin Xcode version

Author: Pattio

.github/workflows/ci.yml

@@ -8,12 +8,15 @@ on:
 
 jobs:
   macos-test:
-    runs-on: macos-latest
+    runs-on: macos-14
 
     steps:
       - name: Check out code
         uses: actions/checkout@v4
 
+      - name: Select Xcode 16.3
+        run: sudo xcode-select -s /Applications/Xcode_15.3.app
+
       - uses: swift-actions/setup-swift@v2
         with:
           swift-version: "6.1"