Prepare release 6.0.0 [skip ci]

CHANGELOG

@@ -1,3 +1,5 @@
+Version 6.0.0 - 2021-05-03
+* Bug fixes (see mercurial logs for details)
 * Add language to contact mechanism
 * Add contact_mechanism as email recipient
 * Rename zip into postal code

COPYRIGHT

@@ -1,6 +1,6 @@
-Copyright (C) 2008-2020 Cédric Krier.
+Copyright (C) 2008-2021 Cédric Krier.
 Copyright (C) 2008-2013 Bertrand Chenal.
-Copyright (C) 2008-2020 B2CK SPRL.
+Copyright (C) 2008-2021 B2CK SPRL.
 Copyright (C) 2008-2019 Udo Spallek.
 Copyright (C) 2008-2011 Korbinian Preisler.
 Copyright (C) 2008-2011 virtual things.

tryton.cfg

@@ -1,5 +1,5 @@
 [tryton]
-version=5.9.0
+version=6.0.0
 depends:
     country
     ir