The ornamental design for a shoulderbag, as shown and described.
FIG. 1 is a perspective view of a shoulder bag showing my 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;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines shown encircling areas with no surface shading depict portions of the article and form no part of the claimed design. The broken lines in the figures shown on claimed surfaces depict stitching and form no part of the claimed design.