fix build

Author: denis-tsv

samples/MvvmSample.Core/ViewModels/IocPageViewModel.cs

@@ -2,6 +2,8 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using MvvmSample.Core.Services;
+
 namespace MvvmSample.Core.ViewModels;
 
 public class IocPageViewModel : SamplePageViewModel