The ornamental design for a door handle, as shown and described.
FIG. 1 is a perspective view of a door handle showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a left side elevational view thereof;
FIG. 4 is a right side elevational view thereof;
FIG. 5 is a top plan view thereof; and,
FIG. 6 is a bottom plan view thereof.
The rear elevational view is not part of the claimed design and is not shown.
The broken lines depict portions of a door handle in which the design in embodied that represent unclaimed subject matter and form no part of the claimed design.