Use new MVVM package

DesktopClock/DesktopClock.csproj

@@ -16,9 +16,9 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="CommunityToolkit.Mvvm" Version="7.1.2" />
     <PackageReference Include="Costura.Fody" Version="5.7.0" PrivateAssets="All" />
     <PackageReference Include="Humanizer.Core" Version="2.14.1" />
-    <PackageReference Include="MvvmLightLibsStd10" Version="5.4.1.1" />
     <PackageReference Include="Newtonsoft.Json" Version="13.0.1" />
     <PackageReference Include="PropertyChanged.Fody" Version="3.4.1" PrivateAssets="All" />
     <PackageReference Include="WpfWindowPlacement" Version="4.0.2" />

DesktopClock/MainViewModel.cs

@@ -1,14 +1,14 @@
 using System;
 using System.ComponentModel;
 using System.Windows.Input;
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
 using DesktopClock.Properties;
-using GalaSoft.MvvmLight;
-using GalaSoft.MvvmLight.CommandWpf;
 using Humanizer;
 
 namespace DesktopClock;
 
-public class MainViewModel : ViewModelBase
+public class MainViewModel : ObservableRecipient
 {
     private readonly SystemClockTimer _systemClockTimer;
     private TimeZoneInfo _timeZone;
@@ -77,5 +77,5 @@ public class MainViewModel : ViewModelBase
         UpdateTimeString();
     }
 
-    private void UpdateTimeString() => RaisePropertyChanged(nameof(CurrentTimeOrCountdownString));
+    private void UpdateTimeString() => OnPropertyChanged(nameof(CurrentTimeOrCountdownString));
 }