I claim the ornamental design for a security patch, as shown and described.
FIG. 1 is a perspective view of a security patch, showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a left-side elevational view thereof, the right-side elevational view being a mirror image thereof;
FIG. 4 is a top plan view thereof; and,
FIG. 5 is a bottom plan view thereof.
The broken lines showing a name in FIGS. 1 and 2 depict environmental matter and form no part of the claimed design. The drawings are shaded for color using the standard symbols for draftsmen with the horizontal lines representing the color blue and the vertical lines representing the color red. The rear elevational view forms no part of the claimed design.