setup(ubuntu/20.04): Support python2.7 and python3
setup(ubuntu/20.04): Support python2.7 and python3

soonho-tri/dreal4,soonho-tri/dreal4,dreal/dreal4,dreal/dreal4,soonho-tri/dreal4,dreal/dreal4,soonho-tri/dreal4,dreal/dreal4