fix(ci): Use latest chromedriver in the docker image

As per the note on the old download page, CfT availability dashboard is the new place to fetch chromedriver from.

This MR changes the Dockerfile to use the JSON API endpoints provided by the dashboard to fetch the latest stable chromedriver.

Though it seems like Google's DEB repository provides the upcoming stable version, the mismatch in the minor version is fine, as compatibility is maintained between the two minor versions.

Closes #704 (closed)