Bump Razor bits in C# extension (#76755)

Brings in serialization change from
dotnet/razor#11386

Author: davidwengier

eng/Directory.Packages.props

@@ -144,7 +144,7 @@
     <PackageVersion Include="NuGet.ProjectModel" Version="6.8.0-rc.112" />
     <PackageVersion Include="Microsoft.TestPlatform.TranslationLayer" Version="$(_MicrosoftTestPlatformVersion)" />
     <PackageVersion Include="Microsoft.TestPlatform.ObjectModel" Version="$(_MicrosoftTestPlatformVersion)" />
-    <PackageVersion Include="Microsoft.AspNetCore.Razor.ExternalAccess.RoslynWorkspace" Version="9.0.0-preview.24555.12" />
+    <PackageVersion Include="Microsoft.AspNetCore.Razor.ExternalAccess.RoslynWorkspace" Version="9.0.0-preview.25064.4" />
 
     <!--
       Analyzers