refactor

Author: Artem-Rzhankoff

HwProj.APIGateway/HwProj.APIGateway.API/Controllers/StatisticsController.cs

@@ -1,5 +1,4 @@
-using System;
-using System.Linq;
+using System.Linq;
 using System.Net;
 using System.Threading.Tasks;
 using HwProj.APIGateway.API.Models.Statistics;

HwProj.APIGateway/HwProj.APIGateway.API/Startup.cs

@@ -1,5 +1,4 @@
-using System;
-using System.Threading.Tasks;
+using System.Threading.Tasks;
 using HwProj.AuthService.Client;
 using HwProj.CoursesService.Client;
 using HwProj.NotificationsService.Client;

HwProj.Common/HwProj.Utils/Auth/GuestModeAuthenticationHandler.cs

@@ -1,5 +1,4 @@
-using System;
-using System.Collections.Generic;
+using System.Collections.Generic;
 using System.Security.Claims;
 using System.Text.Encodings.Web;
 using System.Threading.Tasks;