I claim the ornamental design for a vacuum cleaner, as shown and described.
FIG. 1 is a perspective view of a vacuum cleaner showing my new design;
FIG. 2 is a left-side view of the vacuum cleaner of FIG. 1.
FIG. 3 is a right-side view of the vacuum cleaner of FIG. 1.
FIG. 4 is a front view of the vacuum cleaner of FIG. 1.
FIG. 5 is a rear view of the vacuum cleaner of FIG. 1.
FIG. 6 is a top view of the vacuum cleaner of FIG. 1; and,
FIG. 7 is a bottom view of the vacuum cleaner of FIG. 1.
The portions of the vacuum cleaner shown in broken lines are included for the purpose of illustrating environment and form no part of the claimed design.