The ornamental design for a packet, as shown and described.
FIG. 1 is a perspective view of a packet showing the new design;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a rear elevation view thereof;
FIG. 4 is a top view thereof;
FIG. 5 is a bottom view thereof;
FIG. 6 is a left side view thereof;
FIG. 7 is a right side view thereof; and,
FIG. 8 is a perspective view of the packet in a folded state while in use.
The broken lines shown in FIGS. 1-7 illustrate portions of the packet that form no part of the claimed design. The broken lines illustrating the mug and the hand in FIG. 8 are environment, while the remaining broken lines in FIG. 8 illustrate portions of the packet that form no part of the claimed design.