The ornamental design for a faucet, as shown and described.
FIG. 1 is a perspective view of a faucet showing our design;
FIG. 2 is a front elevational view;
FIG. 3 is a rear elevational view;
FIG. 4 is a side elevational view;
FIG. 5 is a side elevational view;
FIG. 6 is a top plan view; and,
FIG. 7 is a bottom plan view.
The broken line disclosures in the view represents portions of a faucet in which the claimed design is embodied, but which forms no part of the claimed design.