createSnapModifier should use Math.round instead of Math.ceil

[valtism]

Was trying to figure out why my cursor felt off when trying to create a draggable card on a grid:

Screen.Recording.2024-05-15.at.3.30.27.PM.mov

I found out that it was because createSnapModifier uses Math.ceil in its calculation. https://github.com/clauderic/dnd-kit/blob/master/packages/modifiers/src/createSnapModifier.ts

Changing this to Math.round gives the drag handle the feel that it is being used by the cursor, instead of floating off to the bottom right of it. See the fixed version:

Screen.Recording.2024-05-15.at.3.29.59.PM.mov