The ornamental design for a beveragechiller, as shown and described.
FIG. 1 is a front view of a beverage chiller showing my new design, the glass supported by the beverage chiller shown in dotted lines is for intended use only and forms no part of the claimed design;
FIG. 2 is a front and top perspective view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a side view thereof, the opposite side being a mirror image;