The ornamental design for a case, as shown and described.
FIG. 1 is a right, top, front perspective view of a case according to our new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a rear elevational view thereof;
FIG. 5 is a right side elevational view thereof, the left side elevational view thereof being a mirror image of the right side shown; and,
FIG. 6 is a bottom plan view thereof.
The broken line representations in the figures illustrate features of the article to which the design is applied that form no part of the claimed design. The interior broken line in FIG. 6 which defines the bounds of the claimed design forms no part thereof.