The ornamental design for a faucet, as shown and described.
FIG. 1 is a perspective view of a faucet, showing my new design;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a rear elevation view thereof;
FIG. 4 is a side elevation view thereof;
FIG. 5 is a another side elevation view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof, the broken line showing of portions of spout and base portions thereof shown for illustrative purposes only and forming no part of the claimed design.