Comment out PackageReference

Author: sbomer

src/tools/illink/test/Directory.Build.props

@@ -7,8 +7,9 @@
     <LinkerTestDir>$(MSBuildThisFileDirectory)</LinkerTestDir>
   </PropertyGroup>
 
-  <ItemGroup>
+  <!-- Add this PackageReference when the toolset version supports C# 14. -->
+  <!-- <ItemGroup>
     <PackageReference Include="Microsoft.Net.Compilers.Toolset" Version="$(MicrosoftNetCompilersToolsetVersion)" PrivateAssets="all" IsImplicitlyDefined="true" />
-  </ItemGroup>
+  </ItemGroup> -->
 
 </Project>