Apparently useless plot_event.py code became a bug source in latest matplotlib

[texadactyl]

When using plot_event_pipelines(...) or calling make_waterfall_plots() directly, matplotlib, in the latest version, produced this error message: E AttributeError: 'FuncFormatter' object has no attribute 'set_useOffset'

The cause:
ax = plt.gca()
ax.get_xaxis().get_major_formatter().set_useOffset(False) # <--------------------------------

The variable ax is not even used.