py_pizza lw=0 not working

[andrewRowlinson]

The docs are not building for py_pizza examples when some of the linewidth arguments are zero. For example:

mplsoccer/examples/pizza_plots/plot_pizza_colorful.py

Line 82 in bce816c

last_circle_lw=0, # linewidth of last circle

mplsoccer/mplsoccer/py_pizza.py

Lines 316 to 319 in bce816c

	gridlines = ax.yaxis.get_gridlines()
	gridlines[index].set_color(self.last_circle_color)
	gridlines[index].set_linewidth(self.last_circle_lw)
	gridlines[index].set_linestyle(self.last_circle_ls)

The docs error is:
ValueError: At least one value in the dash list must be positive

This seems to be related to:
matplotlib/matplotlib#8821