There is a new pull request by yoctocell against master on the void-packages repository

https://github.com/yoctocell/void-packages matplotlib-3.3.0
https://github.com/void-linux/void-packages/pull/23613

python3-matplotlib: update to 3.3.0
None

A patch file from https://github.com/void-linux/void-packages/pull/23613.patch is attached