The ornamental design for a watch with a qrcode, as shown and described.
FIG. 1 is a perspective view of a watch with a QR code, showing my new design;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a rear elevation view thereof;
FIG. 4 is a left side elevation view thereof;
FIG. 5 is a right side elevation view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines showing a wrist band in the figures depict environmental matter and form no part of the claimed design. The remaining broken lines, including a data portion of the QR code, depict portions of the watch that form no part of the claimed design.