The ornamental design for a drink warmer, as shown and described.
FIG. 1 is a perspective view of the drink warmer, illustrating my new design;
FIG. 2 is a front elevational view of the drink warmer;
FIG. 3 is an elevational view of one side of the drink warmer;
FIG. 4 is an elevational view of the other side of the drink warmer;
FIG. 5 is a top plan view of the drink warmer; and,
FIG. 6 is a rear elevational view of the drink warmer.
The broken lines immediately adjacent the shaded areas represent the bounds of the claimed design, while all other broken lines are directed to environment and are for illustrative purposes only; the broken lines form no part of the claimed design.