tests/task: update for finished() signal
tests/task: update for finished() signal

Tarsnap/tarsnap-gui,shinnok/tarsnap-gui,shinnok/tarsnap-gui,shinnok/tarsnap-gui,Tarsnap/tarsnap-gui,shinnok/tarsnap-gui,Tarsnap/tarsnap-gui,Tarsnap/tarsnap-gui,shinnok/tarsnap-gui,Tarsnap/tarsnap-gui