The ornamental design for a pettoy, as shown and described.
FIG. 1 is a perspective view of a pet toy.
FIG. 2 is a front view of the pet toy.
FIG. 3 is a back view of the pet toy.
FIG. 4 is a left side view of the pet toy.
FIG. 5 is a right side view of the pet toy.
FIG. 6 is a top view of the pet toy; and,
FIG. 7 is a bottom view of the pet toy.
The heavy double dashed lines represent stitching, but form no part of the claimed design. The broken lines in the drawings depict environmental subject matter and form no part of the claimed design.