Update MessagePack (#50954)

Author: marcpopMSFT

Directory.Packages.props

@@ -9,6 +9,7 @@
     <PackageVersion Include="AwesomeAssertions" Version="$(AwesomeAssertionsVersion)" />
     <PackageVersion Include="BenchmarkDotNet" Version="$(BenchmarkDotNetPackageVersion)" />
     <PackageVersion Include="AwesomeAssertions.Json" Version="$(AwesomeAssertionsJsonVersion)" />
+    <PackageVersion Include="MessagePack" Version="2.5.187" />
     <PackageVersion Include="MicroBuild.Plugins.SwixBuild.Dotnet" Version="1.1.87-gba258badda" />
     <PackageVersion Include="Microsoft.ApplicationInsights" Version="$(MicrosoftApplicationInsightsPackageVersion)" />
     <PackageVersion Include="Microsoft.AspNetCore.DeveloperCertificates.XPlat" Version="$(MicrosoftAspNetCoreDeveloperCertificatesXPlatPackageVersion)" />