Remove unnecessary using

Author: MaggieKimani1

src/Microsoft.OpenApi/Reader/OpenApiModelFactory.cs

@@ -5,7 +5,6 @@
 using System.IO;
 using System.Linq;
 using System.Net.Http;
-using System.Runtime.InteropServices.ComTypes;
 using System.Security;
 using System.Text;
 using System.Threading;