We claim the ornamental design for a vacuum cleaner, as shown and described.
FIG. 1 is a perspective view of a vacuum cleaner showing our new design;
FIG. 2 is a top view thereof;
FIG. 3 is a bottom view thereof;
FIG. 4 is a side view thereof;
FIG. 5 is a side view of the opposite side of FIG. 4;
FIG. 6 is a front view thereof; and,
FIG. 7 is a rear view thereof.
The features of the design as claimed by applicants are shown in bold lines. The features shown in dotted lines are not claimed and are provided to indicate the context of the design.