fix client tests to use st.server.listener.Addr.String() instead of hardcoded address
fix client tests to use st.server.listener.Addr.String() instead of
hardcoded address

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