I claim the ornamental design for a projection lamp, as shown and described.
FIG. 1 is a perspective view of the claimed design;
FIG. 2 is a front view of the claimed design shown in FIG. 1;
FIG. 3 is a rear view of the claimed design shown in FIG. 1;
FIG. 4 is a left side view of the claimed design shown in FIG. 1;
FIG. 5 is a right side view of the claimed design shown in FIG. 1;
FIG. 6 is a top view of the claimed design shown in FIG. 1; and,
FIG. 7 is a bottom view of the claimed design shown in FIG. 1.
The ornamental design which is claimed is shown in solid lines in the drawings. The broken lines in the drawings depict portions of the projection lamp that form no part of the claimed design.