refs and cleanup

Author: SimonCropp

src/Directory.Packages.props

@@ -9,7 +9,7 @@
     <PackageVersion Include="NUnit" Version="4.3.2" />
     <PackageVersion Include="NUnit3TestAdapter" Version="5.0.0" />
     <PackageVersion Include="PdfPig" Version="0.1.9" />
-    <PackageVersion Include="Polyfill" Version="7.20.0" />
+    <PackageVersion Include="Polyfill" Version="7.21.0" />
     <PackageVersion Include="ProjectDefaults" Version="1.0.148" />
     <PackageVersion Include="Verify" Version="28.13.0" />
     <PackageVersion Include="Verify.DiffPlex" Version="3.1.2" />