We claim the ornamental design for the infusion packet, as shown and described.
FIG. 1 is a perspective view of the infusion packet showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a right side view thereof, the left side being a mirror image;
FIG. 4 is a top view thereof; and,
FIG. 5 is a bottom view thereof.
The broken lines showing of the cup and spoon in FIG. 1 are for the purpose of illustrating environmental structure and form no part of the claimed design. However, the broken lines showing of the stitching in FIGS. 1 and 2 are part of the claimed design.