The ornamental design for a charger, as shown and described herein.
FIG. 1 is a front elevation view of a charger showing the design;
FIG. 2 is a rear elevation view of the design;
FIG. 3 is a left-side elevation view of the design;
FIG. 4 is a right-side elevation view of the design;
FIG. 5 is a top plan view of the design;
FIG. 6 is a bottom plan view of the design; and,
FIG. 7 is a top, right perspective view of the design.
The charger is shown with symbolic break in the length of the cable. The appearance of any portion of the charger between the break lines forms no part of the claimed design.