$wgAPIModules should extend ApiBase, not ApiQueryBase

I have no idea why this was extending ApiQueryBase since it doesn't use
any methods defined in that class. But at least that makes it easy to
fix.

Change-Id: I632d10322d6f0670577a1fb207927660eab1ac62
(cherry picked from commit f1479162c719182b0ccc408df0962c8040441e02)