fix license text in CopyBuffers benchmark

tests/ImageSharp.Benchmarks/General/CopyBuffers.cs

@@ -1,7 +1,5 @@
-// <copyright file="ArrayCopy.cs" company="James Jackson-South">
+// Copyright (c) Six Labors and contributors.
-// Copyright (c) James Jackson-South and contributors.
 // Licensed under the Apache License, Version 2.0.
-// </copyright>
 
 using System;
 using System.Buffers;