ci: use macos-26 and xcode 26

Author: dcvz

.github/workflows/validate-example.yml

@@ -126,7 +126,7 @@ jobs:
         run: cd example/android && ./gradlew assembleDebug
 
   build-ios:
-    runs-on: macos-15
+    runs-on: macos-26
     steps:
       - name: Checkout
         uses: actions/checkout@v4