Updates dependencies. As the commit messages note, first I got a recent version of the Node base image then I ran yarn upgrade-interactive --latest to update everything but Mapnik, then I updated Mapnik.
Notes
This moves from Mapnik 3 to 4, which definitely comes with some API changes, but we're only using a small slice of the API, so it appears nothing we use was affected.
Updating the linter or, more likely, the linter config package, caused some existing code to start failing, so this fixes that code to bring it in line with the new rules (mainly using parens for arrow functions, even when there's only one argument).
To make sure this worked in production and would deploy cleanly, I set Travis to build on test branches as well as develop. I also changed the Travis build to use the container. It has been installing the Node packages on host and running tests there, but that stopped working with the Mapnik upgrade, because new Mapnik required newer libraries than what are present on the test instances. Using the container in CI seems like a better idea, anyway.
Updates dependencies. As the commit messages note, first I got a recent version of the Node base image then I ran
yarn upgrade-interactive --latestto update everything but Mapnik, then I updated Mapnik.Notes