The ornamental design for a facemask, as shown and described.
FIG. 1 is a front perspective view of a face mask showing my new design;
FIG. 2 is a rear perspective view thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a rear elevational view thereof;
FIG. 5 is a top plan view thereof, the bottom view being a mirror image thereof;
FIG. 6 is a right-side elevational view thereof, the left-side elevational view being a mirror image thereof; and,
FIG. 7 is a front perspective view thereof, wherein the face mask is in its folded state.
The broken lines showing of ear loops in FIGS. 1-7 are included for the purpose of showing environmental structure and form no part of the claimed design.