It is outdated. This one is working:
...
class Family(family.WikimediaFamily):
"""Family class for Wikimania wikis."""
name = 'wikimania'
closed_wikis = [
'2005', '2006', '2007', '2008', '2009', '2010', '2011', '2012', '2013',
'2014', '2015', '2016', '2017', '2018'
]
langs = {
'wikimania': 'wikimania.wikimedia.org'
}
interwiki_forward = 'wikipedia'