Update simple_cov dependency to version 0.6.4
Update simple_cov dependency to version 0.6.4

codeforamerica/follow-all,jasnow/follow-all,jasnow/follow-all,BryanH/follow-all,BryanH/follow-all,jasnow/follow-all,BryanH/follow-all,codeforamerica/follow-all,codeforamerica/follow-all