The ornamental design for a holder for suspending a pump bottle, as shown and described.
FIG. 1 is a perspective view of the holder for suspending a pump bottle.
FIG. 2 is a front elevational view thereof.
FIG. 3 is a rear elevational view thereof.
FIG. 4 is a left side view thereof, the right side view being a mirror image of the left side view.
FIG. 5 is a top plan view thereof.
FIG. 6 is a bottom plan view thereof; and,
FIG. 7 is perspective view showing the design with environmental matter, namely a pump bottle, in broken lines which form no part of the claimed design.