The ornamental design for a faucet, as shown and described.
FIG. 1 is a rear perspective view of a faucet showing my new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a bottom view thereof;
FIG. 4 is a left side view thereof, the opposite side being a mirror image of the side shown;
FIG. 5 is a front elevational view thereof; and,
FIG. 6 is a rear view thereof.
The broken-line disclosure in the view represents a portion of the faucet in which the claimed design is embodied, but which forms no part of the claimed design.