The ornamental design for a whiskeydecanter, as shown and described.
FIG. 1 is a perspective view of a whiskey decanter, showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left side elevational view thereof
FIG. 5 is a right side elevational view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The even broken line showing of the bottom of the whiskey decanter is for the purpose of illustrating portions of the whiskey decanter that form no part of the claimed design. The dot-dash broken lines show a boundary of the claimed design and form no part of the claimed design.