The ornamental design for a petbed, as shown and described.
FIG. 1 is a first perspective view of a pet bed.
FIG. 2 is a top view of the pet bed.
FIG. 3 is a first side view of the pet bed.
FIG. 4 is a second side view of the pet bed.
FIG. 5 is a third side view of the pet bed.
FIG. 6 is a fourth side view of the pet bed.
FIG. 7 is a bottom view of the pet bed; and,
FIG. 8 is a second perspective view of the pet bed, shown with the surface indicia.
The broken lines shown on the bottom surface of the pet bed illustrate texture. The broken lines showing surface indicia in FIG. 8 illustrate portions of the pet bed. The broken lines form no part of the claimed design.