refs and cleanup

Author: SimonCropp

src/Directory.Packages.props

@@ -10,10 +10,10 @@
     <PackageVersion Include="Microsoft.AspNetCore.Components.WebAssembly" Version="8.0.8" />
     <PackageVersion Include="Microsoft.AspNetCore.Components.WebAssembly.DevServer" Version="8.0.8" />
     <PackageVersion Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="8.0.2" />
-    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.0.1" />
+    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.0.0" />
     <PackageVersion Include="Microsoft.NETCore.UniversalWindowsPlatform" Version="6.2.13" />
     <PackageVersion Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.3" />
-    <PackageVersion Include="Polyfill" Version="8.9.1" />
+    <PackageVersion Include="Polyfill" Version="9.0.1" />
     <PackageVersion Include="ProjectDefaults" Version="1.0.162" />
     <PackageVersion Include="PropertyChanged.Fody" Version="4.1.0" />
     <PackageVersion Include="System.Runtime.InteropServices.RuntimeInformation" Version="4.3.0" />