Update dependency of mediawiki_api
Needed to keep this in sync with Wikibase.
FIXME: the gemspec now skips using rubygems.org for
mediawiki_api-wikidata and goes to github directly. That should be
removed when rubygems.org is updated.
Bug: T135884
Change-Id: I1a7b068ea2353206315e6de221b51dddeec999c8