Fix call to Language#convert, thus unbreaking CI
Broken by MW core commit 0f935809fd49345cb41340c1f2be6377c697d293, deprecated in MW 1.35 and hard deprecated since MW 1.40.
Change-Id: I9ba96a88f7cee44a3130e02feca1742bce48e2df
(cherry picked from commit 0a5338c98373cd328ca223583bd8921bf647fcce)