The ornamental design for a mouse, as shown and described.
FIG. 1 is a perspective view of a mouse showing our new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left side elevational view thereof;
FIG. 5 is a right side elevational view thereof; and,
FIG. 6 is a top plan view thereof.
The broken line showing of the elements at the bottom of the mouse are included for the purpose of illustrating unclaimed portions and form no part of the claimed design.