Remove unneeded using

Author: TP125487

CloudConvert.Test/TestJobs.cs

@@ -1,7 +1,6 @@
 using System;
 using System.IO;
 using System.Text.Json;
-using System.Text.Json.Serialization;
 using System.Threading.Tasks;
 using CloudConvert.API;
 using CloudConvert.API.Models;

CloudConvert.Test/TestSignedUrl.cs

@@ -1,4 +1,3 @@
-
 using CloudConvert.API;
 using CloudConvert.API.Models.JobModels;
 using CloudConvert.API.Models.TaskOperations;