The ornamental design for the shaker, as shown and described in FIGS. 1 through 3.
FIG. 1 is a side view of the shaker.
FIG. 2 is a front view of the shaker; and,
FIG. 3 is an opposite side view of FIG. 1.
The broken lines in the FIGS. 4 through 6 show the portions of the shaker that are not to be considered part of the claimed design but for this application the broken lines in the drawings depict unclaimed environmental subject matter.
The shaker is used to separate solids from liquids, and to separate different sized solids from each other.