The ornamental design for a petdoorassembly, as shown and described.
FIG. 1 is a front view of a pet door assembly showing my new design;
FIG. 2 is a rear view of the pet door assembly;
FIG. 3 is a right side view of the pet door assembly;
FIG. 4 is a left side view of the pet door assembly;
FIG. 5 is a top view of the pet door assembly;
FIG. 6 is a bottom view of the pet door assembly;
FIG. 7 is a top front side perspective view of the pet door assembly; and,
FIG. 8 is a top front side perspective view of the pet door assembly in use.
The broken lines in FIG. 2 depict portions of the pet door assembly that form no part of the claimed design. The broken lines in FIG. 8 illustrate environmental structure forming no part of the claimed design.