update script/show_authors.py for Python 3
update script/show_authors.py for Python 3

BubuLK/sfepy,sfepy/sfepy,sfepy/sfepy,BubuLK/sfepy,BubuLK/sfepy,lokik/sfepy,vlukes/sfepy,sfepy/sfepy,rc/sfepy,vlukes/sfepy,lokik/sfepy,vlukes/sfepy,rc/sfepy,rc/sfepy,lokik/sfepy,lokik/sfepy