The ornamental design for a baby bunting, as shown and described.
FIG. 1 is a front view of a baby bunting consisting of a hooded coat portion and a removable leggings portion, the leggings portion attached to the hooded coat portion, showing my design therefor, the bunting lying on a flat surface;
FIG. 2 is a rear view thereof;
FIG. 3 is a front view thereof with the leggings portion removed from the hooded coat portion, the bunting lying on a flat surface; the leggings portion removed from the hooded coat portion; and,
FIG. 4 is a rear view thereof.
The broken lines shown illustrate portions of the baby bunting that form no part of the claimed design.