Update Directory.Packages.props

Author: SimonCropp

src/Directory.Packages.props

@@ -7,7 +7,7 @@
     <PackageVersion Include="MarkdownSnippets.MsBuild" Version="28.0.0-beta.8" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.0.1" />
     <PackageVersion Include="NUnit" Version="4.4.0" />
-    <PackageVersion Include="NUnit3TestAdapter" Version="5.2.0" />
+    <PackageVersion Include="NUnit3TestAdapter" Version="5.2.0" Pinned="true" />
     <PackageVersion Include="ProjectDefaults" Version="1.0.163" />
     <PackageVersion Include="Polyfill" Version="9.3.2" />
     <PackageVersion Include="System.Memory" Version="4.6.3" />