We claim the ornamental design for a siding panel, as shown and described.
FIG. 1 is a perspective view of a siding panel in accordance with our new design.
FIG. 2 is a left side elevation view thereof,
FIG. 3 is a right side elevation view thereof,
FIG. 4 is a front elevation view thereof,
FIG. 5 is a rear elevation view thereof,
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
Areas that appear between the break lines in the figures form no part of the claimed design and indicate that a specific width forms no part of the claimed design.