I claim the ornamental design for a skin treatment apparatus, as shown and described.
FIG. 1 is a perspective view of a skin treatment apparatus.
FIG. 2 is a top view of the skin treatment apparatus.
FIG. 3 is a bottom view of the skin treatment apparatus.
FIG. 4 is a left side view of the skin treatment apparatus.
FIG. 5 is a right side view of the skin treatment apparatus.
FIG. 6 is a front view of the skin treatment apparatus; and,
FIG. 7 is a rear view of the skin treatment apparatus.
The broken line showing of the word “FOREO” represents an environment and is for illustrative purposes only, and the broken lines in FIG. 3 depict portions of the skin treatment apparatus that form no part of the claimed design; the broken lines form no part of the claimed design.