Upgrade

Get the new code (from git)

If you got shimmie from git, then git pull should fetch the latest code (git checkout master then git pull if you're on an old non-master branch).

Once the new Shimmie code is ready, you'll need to make sure all the dependencies are in place and up-to-date via composer install.

Get the new code (.zip)

If you got shimmie from one of the .zip downloads, you'll need to download new code, extract it, then copy across the data folder from the old install into the new one.

Update database schema

This should be automatic - next time the site is loaded, it'll see that the current schema is out of date, and will update it.