Change default plot format to PDF
Addresses the issue with the .png images sometimes displaying the significance dots incorrectly in PlotEquiMap(), as described in https://earth.bsc.es/gitlab/es/sunset/-/issues/82#note_241966
Addresses the issue with the .png images sometimes displaying the significance dots incorrectly in PlotEquiMap(), as described in https://earth.bsc.es/gitlab/es/sunset/-/issues/82#note_241966