The ornamental design for a faucet, substantially as shown and described.
FIG. 1 is a perspective view of a faucet, showing my design.
FIG. 2 is a left side view of the faucet.
FIG. 3 is a right side view of the faucet.
FIG. 4 is a front view of the faucet.
FIG. 5 is a back view of the faucet.
FIG. 6 is a top view of the faucet; and,
FIG. 7 is a bottom view of the faucet.
The broken line on the upper surface indicates an optional feature and does not form part of the claimed design. The broken lines visible in the bottom view define bounds of the claimed design and form no part thereof.