The ornamental design for a sensor, as shown and described.
FIG. 1 is an isometric view of a sensor housing incorporating my ornamental design;
FIG. 2 is a front view of the sensor housing of FIG. 1;
FIG. 3 is a rear view of the sensor housing of FIG. 1;
FIG. 4 is a right side view of the sensor housing of FIG. 1;
FIG. 5 is a top view of the sensor housing of FIG. 1;
FIG. 6 is a left side view of the sensor housing of FIG. 1; and,
FIG. 7 is a bottom view of the sensor housing of FIG. 1.
The broken line showing of the sensor housing is included for the purpose of illustrating environmental structure of the sensor housing and forms no part of the claimed design.