Remove unused usings

Author: Perksey

src/infrastructure/Silk.NET.NUKE/Build.cs

@@ -11,9 +11,7 @@
 using Nuke.Common.Tooling;
 using Nuke.Common.Tools.DotNet;
 using Nuke.Common.Tools.MSBuild;
-using Nuke.Common.Tools.VSTest;
 using static Nuke.Common.Tools.MSBuild.MSBuildTasks;
-using static Nuke.Common.Tools.VSTest.VSTestTasks;
 using static Nuke.Common.Tools.DotNet.DotNetTasks;
 using static Nuke.Common.IO.FileSystemTasks;