Update to Carto 1.2.0

[sommerluk]

It would be great to update to the recent Carto 1.2.0/Mapnik 3.0.22.

Mapnik 3.0.22 has been released.. Also mapnik-reference has been updated to 3.0.22. Furthermore a corresponding new npm package has been published with version number 8.10.0. Also CartoCSS had a new release 1.2.0 which updates its dependencies to Mapnik 3.0.22 respectively mapnik-reference 8.10.0. This CartoCSS release is also available as npm package carto 1.2.0.

However, the Mapnik npm package in version 3.7.2 does only go up to Mapnik 3.0.20, and not Mapnik 3.0.22. And the new 4.x Mapnik npm package seems to align with Mapnik master instead of the 3.0.x branch. Is this a problem?