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 right side view thereof;
FIG. 3 is a left side view thereof;
FIG. 4 is a front view thereof;
FIG. 5 is a rear view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The broken line showing of the various regions of the faucet in and the seams between the faucet spray head and the faucet body represents unclaimed subject matter and forms no part of the claimed design.