The ornamental design for a drum lug, as shown and described.
FIG. 1 is a top perspective view of the drum lug embodying the new design.
FIG. 2 is a top view thereof.
FIG. 3 is a left side view thereof with the opposing side view being a mirror image thereof.
FIG. 4 is a front view thereof.
FIG. 5 is a bottom view thereof; and,
FIG. 6 is a rear view thereof.
Broken lines showing portions of the drum lug are included for the purpose of depicting the environmental structure and form no part of the claimed design.