Upgraded to v2.3.0

Free Radical is now on Mastodon v2.3.0.

Admin tip: if you’ve set UID and/or GID in your .env.production, be sure to update Dockerfile with ARG UID=... and ARG GID=.... If you don’t, you’re going to get lots of permission errors in the docker-compose run --rm web rails assets:precompile part of the upgrade process. Don’t be me.