refs and cleanup

Author: SimonCropp

src/Directory.Packages.props

@@ -6,7 +6,7 @@
   <ItemGroup>
     <PackageVersion Include="MarkdownSnippets.MsBuild" Version="28.2.0" />
     <PackageVersion Include="Magick.NET-Q16-AnyCPU" Version="14.12.0" />
-    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.4.0" />
+    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.5.0" />
     <PackageVersion Include="NUnit" Version="4.5.1" />
     <PackageVersion Include="NUnit3TestAdapter" Version="6.2.0" />
     <PackageVersion Include="Polyfill" Version="10.3.0" />