Remove unused using

Author: jnyrup

Src/FluentAssertions/ObjectAssertionsExtensions.cs

@@ -1,7 +1,6 @@
 using System;
 using System.IO;
 using System.Runtime.Serialization;
-using System.Runtime.Serialization.Formatters.Binary;
 using System.Xml.Serialization;
 using FluentAssertions.Common;
 using FluentAssertions.Equivalency;