- we don't need to run linting twice as we do currently in the Firefox &
Chrome jobs
- also pins the Node version to 12.18.0 so we can be sure what Node
version we're running with
- we recently had an issue where a dependency update broke the
release process because it was building in production mode, but our CI
never ran in this mode and we missed it
- this commit adds a test to run in prod mode so hopefully we catch it
next time
no issue
- using the setup-node action is currently failing because of an
upstream issue - https://github.com/nodejs/node/issues/32683
- this commit switches to using a Docker container