Remove unused usings

Author: RenderMichael

dotnet/src/webdriver/DevTools/DevToolsSession.cs

@@ -17,7 +17,6 @@
 // under the License.
 // </copyright>
 
-using OpenQA.Selenium.DevTools.Json;
 using OpenQA.Selenium.Internal.Logging;
 using System;
 using System.Collections.Concurrent;

dotnet/src/webdriver/JavaScriptEngine.cs

@@ -18,7 +18,6 @@
 // </copyright>
 
 using OpenQA.Selenium.DevTools;
-using OpenQA.Selenium.DevTools.Json;
 using OpenQA.Selenium.Internal;
 using System;
 using System.Collections.Generic;