The ornamental design for a printer, as shown and described.
FIG. 1 is a perspective view of a printer, showing our new design.
FIG. 2 is a front elevational view thereof;
FIG. 3 is a top plan view thereof;
FIG. 4 is a right-side elevational view thereof; and,
FIG. 5 is a left-side elevational view thereof.
The broken lines depict environmental subject matter only and form no part of the claimed design. The dot-dash lines depict a boundary line between claimed and unclaimed subject matter, and form no part of the claimed design. The rear and the bottom of the printer are not part of the claimed design.