Update dependency Microsoft.NET.Test.Sdk to 18.4.0 (#611)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

Directory.Packages.props

@@ -15,7 +15,7 @@
     <PackageVersion Include="FSharp.Core" Version="$(FSCorePackageVersion)" />
     <PackageVersion Include="FSharp.Core.Fluent-4.0" Version="1.0.0.6" />
     <PackageVersion Include="Microsoft.DotNet.GenAPI" Version="7.0.0-beta.24266.2" />
-    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.3.0" />
+    <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.4.0" />
     <PackageVersion Include="Microsoft.SourceLink.GitHub" Version="10.0.201" />
     <PackageVersion Include="Microsoft.Xaml.Behaviors.Wpf" Version="1.1.142" />
     <PackageVersion Include="Newtonsoft.Json" Version="13.0.4" />