Remove macOS/Xcode version pinning in iOS workflow

.github/workflows/ci.yml

@@ -121,9 +121,7 @@ jobs:
 
   build-only-ios:
     name: Build only (iOS)
-    # `macos-13` is required, because the newest Microsoft.iOS.Sdk versions require Xcode 14.3.
-    # TODO: can be changed to `macos-latest` once `macos-13` becomes latest (currently in beta: https://github.com/actions/runner-images/tree/main#available-images)
-    runs-on: macos-13
+    runs-on: macos-latest
     timeout-minutes: 60
     steps:
       - name: Checkout
@@ -137,8 +135,5 @@ jobs:
       - name: Install .NET Workloads
         run: dotnet workload install maui-ios
 
-      - name: Select Xcode 15.2
-        run: sudo xcode-select -s /Applications/Xcode_15.2.app/Contents/Developer
-
       - name: Build
         run: dotnet build -c Debug osu.iOS