Unmanned aerial vehicle

FIG. 1 is a top view of our ornamental design for the unmanned aerial vehicle;

FIG. 2 is a front view thereof;

FIG. 3 is a bottom view thereof;

FIG. 4 is a back view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a right side view thereof; and,

FIG. 7 is a front, top perspective view thereof.

The broken lines shown in the drawings are for the purpose of illustrating portions of the article and form no part of the claimed design.