The ornamental design for a printer, as shown and described.
FIG. 1 is a top right perspective view of a printer, showing our new design;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a top plan view thereof;
FIG. 4 is a right-side elevation view thereof;
FIG. 5 is a left-side elevation view thereof;
FIG. 6 is a rear elevation view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines that are immediately adjacent to the claim represent the bounds of the claimed design; the broken lines form no part of the claimed design.