There are plenty of metal polishing/buffing compounds around, as well as buffing wheels for bench top grinders, angle grinders, and roto-tools which all can be Googled.
If you have an colored anodized finish, a bit of paint or nail polish might work. Use a fine brush to paint some on, then wipe off anything that overflows the scratch, which can be difficult to impossible to do.
The problem with either of these is: will it match your existing laptops finish? I'm afraid that anything you do will likely make a larger, more noticeable mark than the scratch.
I used to be a computer tech and still work with/on computers (for a total of over 20 years) and scratches are going to continue to happen. No matter how gentle you think you are with your laptop, scratches are going to happen. Most of them will appear more subtly than this one, but they'll happen. I actually recommend against laptops as a professional opinion, since they are more likely to be damaged and destroyed than a desktop.
The best thing (and probably hardest thing) is to accept it, learn to ignore it, and just continue on as if it never happened.
Or, throw a sticker over it. Favorite band, favorite sports team, favorite video game, whatever, as long as you don't mind it.