improved TestFutureTimestampHandling
improved TestFutureTimestampHandling

should no longer have nondeterministic failues in the CI

fix #1211

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