[cd] update xcode version to 15.2

Author: nan-li

.github/workflows/cd.yml

@@ -21,7 +21,7 @@ jobs:
       - name: setup xcode
         uses: maxim-lobanov/setup-xcode@v1
         with:
-          xcode-version: '14.1'
+          xcode-version: '15.2'
       - name: Checkout OneSignal-iOS-SDK
         uses: actions/checkout@v4
         with: