The ornamental design for a bottleholder, as shown and described.
FIG. 1 is a perspective view of a bottle holder showing my new design, the broken line showing of a bottle being for purposes of illustrating environmental structure forming no part of the claimed design;
FIG. 2 is a front elevation view, the rear, left side, and right side elevation views being identical thereto; and,
FIG. 3 is a top plan view, the bottom plan view being identical thereto.