Update CsWinRT to latest stable

Author: Sergio0694

src/CommunityToolkit.Mvvm/CommunityToolkit.Mvvm.csproj

@@ -53,7 +53,7 @@
 
   <!-- Reference CsWinRT when targeting Windows, to get the latest source generators -->
   <ItemGroup Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net8.0-windows10.0.17763.0'))">
-    <PackageReference Include="Microsoft.Windows.CsWinRT" Version="2.1.0-prerelease.240801.1" PrivateAssets="all" />
+    <PackageReference Include="Microsoft.Windows.CsWinRT" Version="2.1.1" PrivateAssets="all" />
   </ItemGroup>
 
   <!-- Reference the various multi-targeted versions of the source generator project (one per Roslyn version), and the code fixer -->