github: Ensure range listers do not override shared lister state

Recent changes in base Lister class implementation turn the call to
self.scheduler.update_lister mandatory to update the last termination
date for a lister.

It has some side effects on the GitHub lister as there is one incremental
instance plus multiple range ones relisting previously discovered repos
executed in parallel.

Range GitHub listers should not override the shared incremental lister
state as StaleData exceptions might be raised otherwise, so override
the set_state_in_scheduler Lister method to ensure that.