The ornamental design for a vanity, as shown and described.
FIG. 1 is a perspective view of a vanity;
FIG. 2 is a top plan view of the vanity of FIG. 1;
FIG. 3 is a front view of the vanity of FIG. 1;
FIG. 4 is a side view of the vanity of FIG. 1;
FIG. 5 is a rear view of the vanity of FIG. 1; and,
FIG. 6 is a sectional view of the leg of the vanity of FIG. 1.
The broken lines showing the rear surface, faucet and drain hole are included for the purpose of illustrating a portion of the vanity that forms no part of the claimed design.