US D567932 S1
The ornamental design for a ventilation grille, as shown and described.
FIG. 1 is a perspective view of the ventilation grille.
FIG. 2 is bottom view thereof;
FIG. 3 is a left side view thereof;
FIG. 4 is a right side view thereof;
FIG. 5 is a front view thereof; and,
FIG. 6 is a rear view thereof.
The broken line showing of parts of the drawings depicts use and environment and forms no part of the claimed design.