For a very rough solution (there's definitely some room for refinement), I'd suggest using two events to push the player away slightly:
Is Player overlapping Wall at offset (-1,0) -> Player Set x to self.x+1
Is Player overlapping Wall at offset (1,0) -> Player Set x to self.x-1
I'd also suggest adding in a condition to check the wall's angle, otherwise the player vibrates while pushing against flat walls.