The ornamental design for a semi-rigid container, as shown and described.
FIG. 1 is a perspective view of the semi-rigid container of the present invention;
FIG. 2 is a front elevation view of the semi-rigid container of the present invention, with the rear elevation view a mirror image of the front elevation view;
FIG. 3 is a left elevation view of the semi-rigid container of the present invention, with the right elevation view a mirror image of the left elevation view;
FIG. 4 is a top plan view of the semi-rigid container of the present invention; and,
FIG. 5 is a bottom plan view of the semi-rigid container of the present invention.
The broken lines in FIG. 1 represent environmental structure in the form of contents within the semi-rigid container and form no part of the claimed design. The broken lines on the semi-rigid container showing a rectangular seal in FIGS. 1, 4, and 5 represent unclaimed portions of the design. The broken lines form no part of the claimed design.