use current year of packaging in manpage

There are tests that verify if the manpage contains the current year. As
auto-testing is now enabled during package build, I have to patch this
otherwise the package fails to build.

diceware.1

 .\" Man page generated from reStructuredText.
 .
-.TH DICEWARE 1 "September 2017" "diceware 0.9.3" "User Commands"
+.TH DICEWARE 1 "September 2018" "diceware 0.9.3" "User Commands"
 .SH NAME
 diceware \- create passphrases
 .
@@ -135,7 +135,7 @@ passphrase.
 .SH COPYRIGHT
 .sp
 diceware \-\- Python implementation
-Copyright (C) 2015\-2017 Uli Fouquet and contributors
+Copyright (C) 2015\-2018 Uli Fouquet and contributors
 .sp
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by

diceware/__init__.py

@@ -53,7 +53,7 @@ def print_version():
     """Output current version and other infos.
     """
     print("diceware %s" % __version__)
-    print("Copyright (C) 2015-2017 Uli Fouquet")
+    print("Copyright (C) 2015-2018 Uli Fouquet")
     print("diceware is based on suggestions of Arnold G. Reinhold.")
     print("See http://diceware.com for details.")
     print("'Diceware' is a trademark of Arnold G. Reinhold.")