acb_hypgeom_pfq_series_sum_forward: fix regularized=1, q=0 case
acb_hypgeom_pfq_series_sum_forward: fix regularized=1, q=0 case

argriffing/arb,argriffing/arb,fredrik-johansson/arb,fredrik-johansson/arb,argriffing/arb,pascalmolin/arb,pascalmolin/arb,pascalmolin/arb