The ornamental design for a robot, as shown and described.
FIG. 1 is a front perspective view of a robot showing our new design;
FIG. 2 is a rear perspective view thereof;
FIG. 3 is another rear perspective view thereof;
FIG. 4 is a front view thereof;
FIG. 5 is a rear view thereof;
FIG. 6 is a right side view thereof, the left side view being a mirror image thereof;
FIG. 7 is a top view thereof; and,
FIG. 8 is a bottom view thereof.
The drawings include grayscale surface shading which illustrates contour, not any particular color. The drawings include shadows and reflections which indicate contour, not surface ornamentation. A transparent face mask of the robot, a profile of which is visible in FIGS. 2 and 6, is herein represented in broken lines as environment for illustrative purposes only and forms no part of the claimed design.