The ornamental design for a valance, as shown and described.
FIG. 1 is a front, bottom perspective view of a valance showing the claimed design;
FIG. 2 is a bottom view of FIG. 1;
FIG. 3 is a top view of FIG. 1;
FIG. 4 is a right side view of FIG. 1;
FIG. 5 is a left side view of FIG. 1;
FIG. 6 is a front view of FIG. 1; and,
FIG. 7 is a rear view of FIG. 1.
The dot-dash broken lines represent the boundary of the claim and form no part of the claim. The remaining broken lines depict portions of the valance that form no part of the claimed design.