sitespeedio/sitespeed.io v12.2.0 on GitHub

Updated the Docker container to use Firefox 74.
Introduced a new slim container with only Firefox. Look for the version tag + slim sitespeedio/sitespeed.io:12.2.0-slim. The container is based on Buster slim and we try to keep it as small as possible. The test runs Firefox headless without XVFB and without FFMPeg/ImageMagick so no Visual Metrics in this container for now #2913.
Cleaned up the dependency tree to make the container (and install) smaller on the default container #2911.
Use coach-core instead of coach #2912.
Use Browsertime 8.2.0 that removed the sharp dependency and instead uses jimp.
The GPSI-plugin in the plus1 container now uses the GPSI backend that uses Lighthouse. New structure of metrics so you will need to update your graphs. See GPSI #20. Also metrics is tagged by desktop/mobile #2917 in Graphite/InfluxDB.
Updated copy and show more total transfer sizes for transparency in the sustainable plugin, thank you Chris Adams #2909, #2919 and #2920. Also updated co2.js to the newest version not using SQLite #2922