fix threadgroup test typo
fix threadgroup test typo

mtlynch/Sia,NebulousLabs/Sia,mharkus/Sia,NebulousLabs/Sia,MrStrong/Sia,mtlynch/Sia,ericflo/Sia,ChrisSchinnerl/Sia,ChrisSchinnerl/Sia,mharkus/Sia,MrStrong/Sia,mnsl/Sia,mnsl/Sia,ericflo/Sia