Description of the desired feature
Since it's one of the most frequently used geo datasets to plot as well as based on a comment in the forum (https://forum.generic-mapping-tools.org/t/borders-plate-tectonics/1946) I think it would be useful to have the plate boundaries of Bird (2002) as a built-in dataset in GMT/PyGMT.
Are you willing to help implement and maintain this feature? Yes (but first discuss)