I claim the ornamental design for a dining chair, as shown and described.
FIG. 1 is a front perspective view of a dining chair;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a right elevational view thereof;
FIG. 5 is a top plan view thereof; and,
FIG. 6 is bottom plan view thereof.
The left and right sides of the dining chair are mirror images of one another.
The broken lines showing of the three brackets on the bottom of the seat in FIG. 6 are for illustrative purposes only and form no part of the claimed design.