The ornamental design for an herbholder, as shown and described.
FIG. 1 is a front, top, left side perspective view of the herb holder of the new design;
FIG. 2 is a front view thereof;
FIG. 3 is a front, top, left side perspective view;
FIG. 4 is a front view thereof;
FIG. 5 is a front, top perspective view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof;
FIG. 8 is a left side view thereof, the right side being a mirror image; and,
FIG. 9 is a rear view thereof.
The broken lines showing structural elements in the drawings are included for the purpose of illustrating non-claimed subject matter, and form no part of the claimed design.