The ornamental design for a pushbroom, as shown and described.
FIG. 1 is a top, front, right perspective view of a push broom showing our new design;
FIG. 2 is an enlarged top, front, right perspective view thereof with additional unclaimed subject matter omitted;
FIG. 3 is a front view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a right side view thereof;
FIG. 7 is a top view thereof; and,
FIG. 8 is a bottom view thereof.
The break lines shown only in FIGS. 2-8 as broken lines are imaginary lines that form no part of the push broom or the claimed design. The broken lines immediately adjacent to the shaded area represent unclaimed boundaries of the design. The broken lines showing the remainder of the push broom represent unclaimed subject matter and form no part of the claimed design.