Just upgraded the Green Plenty Mastodon instance to 3.5.1

Had to bump Ruby version to 3.0.3 (which is painless if you know the rbenv command)

The rest of it seems to have gone ok

I did reboot, though, rather than just run the restart commands.

I also did Ubuntu updates of everything so the machine is up to date too.

Digital Ocean's turnkey Mastodon is version 3.1.3.

Next thing is to lock things down a bit. I'm going to borrow what's in https://freeradical.zone/about/more - seems like a good starter.