Remove unused using.

Author: claudiamurialdo

dotnet/src/dotnetcore/GxPdfReportsCS/PDFReportItext8.cs

@@ -3,7 +3,6 @@
 using System.Collections.Generic;
 using System.Globalization;
 using System.IO;
-using System.Linq;
 using System.Text;
 using GeneXus;
 using iText.Barcodes;