fix: weekbased calculation pdf report

with this change the time calculations for pdf reports should be better
line with the reports send as "week_report"

Backend/models/absence.go

@@ -63,7 +63,7 @@ func (a *Absence) GetWorktime(u User, base WorktimeBase, includeKurzarbeit bool)
 		return u.ArbeitszeitProTagFrac(float32(a.AbwesenheitTyp.WorkTime) / 100)
 	case WorktimeBaseWeek:
 		if a.AbwesenheitTyp.WorkTime <= 0 && includeKurzarbeit {
-			return u.ArbeitszeitProTagFrac(0.2)
+			return u.ArbeitszeitProWocheFrac(0.2)
 		} else if a.AbwesenheitTyp.WorkTime <= 0 {
 			return 0
 		}