The ornamental design for a faucet, as shown and described.
FIG. 1 is a front perspective view of a faucet showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a right side view thereof;
FIG. 5 is a left side view thereof; and,
FIG. 6 is a top view thereof.
The broken line showing of the oval-shaped region in FIGS. 1 and 4, the washer adjacent the base of the faucet, and the remainder of the faucet in FIG. 1-7 represents unclaimed subject matter and forms no part of the claimed design.