Use macOS 15 to include visionOS SDK

Author: kateinoigakukun

.github/workflows/main.yml

@@ -55,7 +55,7 @@ jobs:
       - run: swift test --sanitize address
 
   build-xcode:
-    runs-on: macos-14
+    runs-on: macos-15
     steps:
       - uses: actions/checkout@v4
       - run: xcrun xcodebuild -skipMacroValidation -skipPackagePluginValidation build -scheme WasmKit-Package -destination generic/platform=macOS