Update matplotlib to 3.1.1#314

pyup-bot wants to merge 1 commit intomasterFordyceLab/AcqPack:masterfrom

pyup-update-matplotlib-2.0.2-to-3.1.1FordyceLab/AcqPack:pyup-update-matplotlib-2.0.2-to-3.1.1Copy head branch name to clipboard