Remove unneded using namespace

Author: JustinGrote

test/PowerShellEditorServices.Test.E2E/LanguageServerProtocolMessageTests.cs

@@ -13,7 +13,6 @@
 using Microsoft.PowerShell.EditorServices.Handlers;
 using Microsoft.PowerShell.EditorServices.Services.Configuration;
 using Microsoft.PowerShell.EditorServices.Services.PowerShell;
-using Microsoft.VisualStudio.TestPlatform.ObjectModel.Engine.ClientProtocol;
 using Newtonsoft.Json.Linq;
 using OmniSharp.Extensions.LanguageServer.Protocol;
 using OmniSharp.Extensions.LanguageServer.Protocol.Client;