Remove unnecessary using statement

Author: ardalis

src/GuardClauses/GuardAgainstOutOfRangeExtensions.cs

@@ -4,7 +4,6 @@
 using System.Linq;
 using System.Diagnostics.CodeAnalysis;
 using System.Runtime.CompilerServices;
-using GuardClauses;
 
 namespace Ardalis.GuardClauses;