removing unused using

Author: FabianGosebrink

SampleWebApiAspNetCore/Startup.cs

@@ -7,7 +7,6 @@
 using Microsoft.AspNetCore.Mvc.ApiExplorer;
 using Microsoft.AspNetCore.Mvc.Infrastructure;
 using Microsoft.AspNetCore.Mvc.Routing;
-using Microsoft.AspNetCore.Mvc.Versioning;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;