I claim the ornamental design for a broom cover, as shown and described.
FIG. 1 is a front view of a broom cover showing my new design; and,
FIG. 2 is a back view thereof.
The broken lines shown in the drawings illustrate portions of the broom cover and form no part of the claimed design.
The broom cover is made of fabric and therefore has no substantial thickness. The gathers are shown in slightly different configurations between the two views.