Update Copyright_header.txt

Copyright_header.txt

@@ -5,5 +5,5 @@ Copyright (C) 1996-2018 Potsdam Institute for Climate Impact Reserach (PIK)
 authors and contributors see AUTHOR file.
 This file is part of 4C and is licensed under BSD-2-Clause. 
 See LICENSE file or under http://www.https://opensource.org/licenses/BSD-2-Clause   
-Contact: https://gitlab.pik-potsdam.de/XXXXXXXXXXXXXXXXXXXXXXXXXXX
+Contact: https://gitlab.pik-potsdam.de/foresee/4C
 ********************************************************************************
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