I claim the ornamental design for a sewing ruler, as shown and described.
FIG. 1 is a perspective view showing my new design.
FIG. 2 is a front view thereof;
FIG. 3 is a top perspective view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a side view thereof;
FIG. 6 is a top elevation view thereof;
FIG. 7 is a bottom elevation view thereof;
FIG. 8 is a right elevation view thereof;
FIG. 9 is a left elevation view thereof; and,
FIG. 10 is an exploded view thereof.
The shading lines shown in the drawings represent the approximate three-dimensional contour of the design, and are not intended to indicate surface decoration.