The ornamental design for a bassinet, as shown and described.
FIG. 1 is a perspective view of the bassinet embodying my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a top plan view thereof;
FIG. 5 is a bottom plan view thereof;
FIG. 6 is a right side view thereof; and,
FIG. 7 is a left side view thereof.
FIGS. 1-7 show a bassinet tub and portions of the bassinet in broken lines. The broken lines are shown for environmental purposes and form no part of the claimed design.