Remove unused usings.

src/AST/Class.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Diagnostics;
 using System.Linq;
 
 namespace CppSharp.AST

src/Generator/Passes/GetterSetterToPropertyPass.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Diagnostics;
 using System.Linq;
 using CppSharp.AST;
 

src/Generator/Passes/Pass.cs

@@ -1,5 +1,4 @@
-
+using CppSharp.AST;
-using CppSharp.AST;
 using CppSharp.Generators;
 
 namespace CppSharp.Passes