Hi Jean, it's down to how you feel, but a week is not long enough for any physiological adaptation to take place from a long run. If you do another long run, it means all the benefit is psychological - you'll feel better prepared, for sure.
You'll read plenty of people saying that you should do your last long run two or even three weeks out from your race. It's swings and roundabouts. If you cut your long run to 8 miles this weekend, you'll start your HM feeling fresher. But if you think you'll be held back by self-doubt, then go ahead and run the longer distance, making sure it is nice and steady. Don't try to run at faster tha HM pace this weekend.