Update src/MSBuild/MSBuild.csproj

Co-authored-by: Rainer Sigwald <raines@microsoft.com>

Author: Forgind

src/MSBuild/MSBuild.csproj

@@ -336,7 +336,7 @@
     </Task>
   </UsingTask>
 
-  <Target Name="ValidateMSBuildPackageDependencyVersions" BeforeTargets="AfterBuild" Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'" >
+  <Target Name="ValidateMSBuildPackageDependencyVersions" AfterTargets="PrepareForBuild" Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'" >
     <ValidateMSBuildPackageDependencyVersions AppConfig="@(AppConfigWithTargetPath)" AssemblyPath="$(OutputPath)%(_TargetFrameworks.Identity)" />
   </Target>