far.py: fix issue in calling RankingStat with using new kwarggen function
This fixes two issues introduced by commit cf94c2d1:
kwarggento be a generator rather than return a dictionary. This appears to be the intended behavior, rather than what was implemented.
- Changed the call to
RankingStat.__call__()to pass in
min_instrumentsas well. This caused an issue where the number of input arguments to