Add required namespace

Author: raman-m

test/Ocelot.AcceptanceTests/AggregateTests.cs

@@ -10,6 +10,7 @@
 using Microsoft.AspNetCore.TestHost;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
+using Newtonsoft.Json;
 using Ocelot.AcceptanceTests.Authentication;
 using Ocelot.Configuration.File;
 using Ocelot.DependencyInjection;