We claim the ornamental design for a generator set, as shown and described.
FIG. 1 is a top, front, left perspective view of a generator set.
FIG. 2 is a top, rear, right perspective view of the generator set of FIG. 1.
FIG. 3 is a front view of the generator set of FIG. 1.
FIG. 4 is a rear view of the generator set of FIG. 1.
FIG. 5 is a left side view of the generator set of FIG. 1.
FIG. 6 is a right side view of the generator set of FIG. 1.
FIG. 7 is a top view of the generator set of FIG. 1; and,
FIG. 8 is a bottom view of the generator set of FIG. 1.
The ornamental design which is claimed is shown in solid lines in the drawings. Any broken lines in the figures illustrate portions of the generator set that form no part of the claimed design.