Hotfix for Falcon and Walker (Patreon)

As I continue cataloguing and adjusting all the snapcore pieces (over 100 at this point), I notice things that can be improved. Printing more of the walker snap/fit joint that the falcon also uses for the wings made me realize it was a bit of a hard push. I made it so that the shoulderpad of the walker would not slide off, but I might have overdone it. Attached an easier version, with a small groove rather than nothing at the beginning of the slide-in part.