WeasyPrint: "There are known rendering problems and missing features with cairo < 1.15.4" error

[vccolombo]

WeasyPrint has been fully released since the last commit to master. Now, it requires an updated version of Cairo, which is not available by just apt upgrading in Ubuntu 16. Also, it requires installing libcairo2-dev package, and I think this might be an unnecessary burden to users

My suggestion would be to update requirements.txt to make WeasyPrint install the version we used before

weasyprint==0.42.3

Do you think using an outdate version of it would be bad?

Thanks!