Update dndetaMFTPbPb.cxx

new try to fix copyright header

Author: gbencedi

PWGMM/Mult/Tasks/dndetaMFTPbPb.cxx

@@ -1,13 +1,14 @@
-// Copyright 2020-2022 CERN and copyright holders of ALICE O2.
-// See https://alice-o2.web.cern.ch/copyright for details of the copyright
-// holders. All rights not expressly granted are reserved.
+// Copyright 2019-2020 CERN and copyright holders of ALICE O2.
+// See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
+// All rights not expressly granted are reserved.
 //
 // This software is distributed under the terms of the GNU General Public
 // License v3 (GPL Version 3), copied verbatim in the file "COPYING".
 //
 // In applying this license CERN does not waive the privileges and immunities
 // granted to it by virtue of its status as an Intergovernmental Organization
 // or submit itself to any jurisdiction.
+//
 ///
 /// \brief  Task for calculating dNdeta in Pb-Pb collisions using MFT detector
 /// \author Gyula Bencedi, gyula.bencedi@cern.ch