The ornamental design for a dispenser, as shown and described.
FIG. 1 is a perspective view of a dispenser showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a right side view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The broken lines are shown for the purpose of illustrating environmental subject matter of an exemplary dispenser and form no part of the claimed design.