The ornamental design for the humidifier, as shown and described.
FIG. 1 is a perspective view of a humidifier;
FIG. 2 is a front view of the humidifier shown in FIG. 1;
FIG. 3 is a back view of the humidifier shown in FIG. 1;
FIG. 4 is a top view of the humidifier shown in FIG. 1;
FIG. 5 is a bottom view of the humidifier shown in FIG. 1;
FIG. 6 is a left view of the humidifier shown in FIG. 1; and,
FIG. 7 is a right view of the humidifier shown in FIG. 1.
The broken line showing of parts of the drawings is included for the purpose of illustrating use and environment and forms no part of the claimed design.