remove unused usings

Author: GreemDev

src/Server/Controllers/DownloadController.cs

@@ -1,5 +1,3 @@
-using System.Net;
-using Gommon;
 using Microsoft.AspNetCore.Mvc;
 using Ryujinx.Systems.Update.Common;
 using Ryujinx.Systems.Update.Server.Services.GitLab;

src/Server/Helpers/Http/Endpoint/PaginatedEndpoint.Builder.cs

@@ -1,5 +1,4 @@
-using System.Net.Http.Json;
-using System.Text.Json.Serialization.Metadata;
+using System.Text.Json.Serialization.Metadata;
 using Gommon;
 using Ryujinx.Systems.Update.Server.Services;