Update dependency Microsoft.NET.Test.Sdk to 18.8.1

Author: renovate[bot]

tests/ngr/dotnet-csharp/demo.csproj

@@ -9,7 +9,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.8.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.8.1" />
     <PackageReference Include="xunit" Version="2.9.3" />
     <PackageReference Include="xunit.runner.visualstudio" Version="3.1.5" />
     <PackageReference Include="coverlet.collector" Version="10.0.1" />