refs and cleanup

Author: SimonCropp

src/Directory.Packages.props

@@ -18,6 +18,6 @@
     <PackageVersion Include="Verify" Version="30.0.0" />
     <PackageVersion Include="Verify.DiffPlex" Version="3.1.2" />
     <PackageVersion Include="Verify.NUnit" Version="30.0.0" />
-    <PackageVersion Include="Microsoft.Sbom.Targets" Version="3.1.0" />
+    <PackageVersion Include="Microsoft.Sbom.Targets" Version="4.0.2" />
   </ItemGroup>
 </Project>