Remove unnecessary using

Author: MaggieKimani1

src/Microsoft.OpenApi/Any/OpenApiPrimitive.cs

@@ -2,7 +2,6 @@
 // Licensed under the MIT license. 
 
 using System;
-using System.Reflection;
 using System.Text;
 using Microsoft.OpenApi.Exceptions;
 using Microsoft.OpenApi.Properties;