This is a minor release which pins HighCharts to version 10
While unlikely something will go wrong, please make sure you have a backup your weewx.conf configuration.
Download:
wget https://github.com/poblabs/weewx-belchertown/releases/download/weewx-belchertown-1.3.1/weewx-belchertown-release.1.3.1.tar.gz
Then run:
sudo wee_extension --install weewx-belchertown-release-1.3.1.tar.gz
Configure the weewx.conf pre-requisites and restart weewx when done.