I couldn't install labours but made it work with this docker command:
docker run --rm -v "$PWD":"$PWD" -w "$PWD" -u 1000 srcd/hercules hercules --burndown --pb . | docker run --rm -i -v "$PWD":"$PWD" -w "$PWD" -u 1000 srcd/hercules labours -f pb -m burndown-project --resample month -o git.png
it will create a ./git/project.png file. Hope that helps save some time to people, I couldn't make the normal install to work but that command does exactly what I wanted.