Adjust markers' label offsets for matplotlib>=3.11 #106

matplotlib 3.11 changed the font handling, resulting in the numbers/letters drawn on the plot markers to be offsetted (when using markers='numbers' or markers='letters'). They are already drawn with manually defined offset values, so these need to be adjusted for newer matplotlib version (keeping the old values for older matplotlib versions).

A quick workaround is to force the matplotlib version with pip install matplotlib==3.10.9