The ornamental design for an adaptor, as shown and described.
FIG. 1 is a front, left side and top perspective view of an adaptor showing our new design.
FIG. 2 is a front elevational view thereof, the rear elevational view being a mirror image thereof.
FIG. 3 is a left side elevational view thereof, the other side being a mirror image thereof; and,
FIG. 4 is a front, right side and bottom perspective view thereof.
The broken line showing in the drawings is included for environmental purposes only to illustrate portions of the adaptor that form no part of the claimed design.