fix legend issues with pie3 code-examples in ssim_baselines/matlab/code-examples/data-distribution-plots/pie3/

[gilbertogalvis]

This PR fix issues related to legend using pie3 function. Specifically working with plot_2_0_compare_two_pie_charts.m example in https://github.com/plotly/ssim_baselines/tree/main/matlab/code-examples/data-distribution-plots/pie3

Code to test

y2010 = [50 0 100 95];
y2011 = [65 22 97 120];
labels = {'Investments','Cash','Operations','Sales'};
t = tiledlayout (2,1);
ax1 = nexttile;
pie3(ax1,y2010)
title('2010')
legend(labels)

ax2 = nexttile;
pie3(ax2,y2011)
title('2011')
legend(labels);

f = fig2plotly(gcf, 'offline', 0, 'TreatAs', 'pie3');

Result must look as follow

Link to chart-studio bellow

https://chart-studio.plotly.com/~galvisgilberto/3708/_2010/#/