Remove unused import

Author: caaavik-msft

src/BenchmarkDotNet/Toolchains/DotNetCli/DotNetCliCommand.cs

@@ -2,7 +2,6 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
-using System.IO;
 using System.Text;
 using BenchmarkDotNet.Characteristics;
 using BenchmarkDotNet.Extensions;