The ornamental design for the pail shelf, as shown and described.
FIG. 1 is an upper perspective view of the pail shelf showing my design.
FIG. 2 is a top plan view thereof;
FIG. 3 is a bottom plan view thereof;
FIG. 4 is a front elevation view thereof;
FIG. 5 is a back elevation view thereof;
FIG. 6 is a side view thereof;
FIG. 7 is an opposite side view thereof; and,
FIG. 8 is another perspective view thereof, showing attachment to a ladder.
The pail shelf is an attachment for a ladder. The broken lines in FIG. 8 are presented for illustrative purposes only and form no part of the claimed design.