Bump CommunityToolkit.Mvvm from 8.3.2 to 8.4.0 in /samples (#348)

Author: dependabot[bot]

src/CommunityToolkit.Maui.Markup.Benchmarks/CommunityToolkit.Maui.Markup.Benchmarks.csproj

@@ -18,7 +18,7 @@
   <ItemGroup>
     <PackageReference Include="BenchmarkDotNet" Version="0.14.0" />
     <PackageReference Include="BenchmarkDotNet.Diagnostics.Windows" Version="0.14.0" Condition="'$(OS)' == 'Windows_NT'" />
-    <PackageReference Include="CommunityToolkit.Mvvm" Version="8.3.2" />
+    <PackageReference Include="CommunityToolkit.Mvvm" Version="8.4.0" />
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="4.12.0" />
     <PackageReference Include="Microsoft.Maui.Controls" Version="$(MauiPackageVersion)" />
   </ItemGroup>