Update Directory.Packages.props

Author: SimonCropp

src/Directory.Packages.props

@@ -14,10 +14,10 @@
     <PackageVersion Include="Polyfill" Version="9.3.1" />
     <PackageVersion Include="ProjectDefaults" Version="1.0.163" />
     <PackageVersion Include="Resourcer.Fody" Version="1.8.1" />
-    <PackageVersion Include="System.Collections.Immutable" Version="8.0.0" />
+    <PackageVersion Include="System.Collections.Immutable" Version="8.0.0" Pinned="true" />
     <PackageVersion Include="Serilog" Version="4.3.0" />
     <PackageVersion Include="Serilog.Sinks.File" Version="7.0.0" />
-    <PackageVersion Include="System.Management" Version="8.0.0" />
+    <PackageVersion Include="System.Management" Version="8.0.0" Pinned="true" />
     <PackageVersion Include="System.Runtime.InteropServices.RuntimeInformation" Version="4.3.0" />
     <PackageVersion Include="Verify.DiffPlex" Version="3.1.2" />
     <PackageVersion Include="Verify.ImageMagick" Version="3.8.0" />