fix deprecated packages warning

Author: Bertk

src/coverlet.msbuild.tasks/coverlet.msbuild.tasks.csproj

@@ -42,6 +42,7 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.Extensions.DependencyInjection" />
     <PackageReference Include="Microsoft.Build.Utilities.Core" VersionOverride="$(MicrosoftBuildVersion)" PrivateAssets="all" ExcludeAssets="Runtime" />
+    <PackageReference Include="System.Security.AccessControl" />
   </ItemGroup>
 
   <ItemGroup>