Ensure, we display current year in version info.

tests/test_diceware.py

 from __future__ import unicode_literals
+import datetime
 import os
 import pytest
 import sys
@@ -151,6 +152,13 @@ class TestDicewareModule(object):
         assert err == ''
         assert __version__ in out
 
+    def test_print_version_current_year(self, capsys):
+        # in version infos we display the current year
+        print_version()
+        expected = '(C) %s' % (datetime.datetime.now().year)
+        out, err = capsys.readouterr()
+        assert expected in out
+
     def test_handle_options(self):
         # we can get help
         with pytest.raises(SystemExit) as exc_info: