修正：Unregister时没有清理Classes中的指针

Author: jozhn

Plugins/UnLua/Source/UnLua/Private/Registries/ClassRegistry.cpp

@@ -267,6 +267,7 @@ namespace UnLua
         const auto Desc = Find(Class);
         if (!Desc)
             return;
+        Classes.Remove(Class);
         Desc->UnLoad();
         Unregister(Desc, true);
     }