Pockethold uses, as should, create-project flarum/flarum to do the initial installment of flarum/flarum.
Since create-project only can be run in an empty folder, this means that running the script again will not work.
An update is to be done with composer update, and after this, php flarum cache:clear. (or manually deleting js and css in the assets folder). It should be easy to simply do an update flarum version of pockethold though.
However, I am not composer'savy enough to take an uneducated guess at how it would affect extensions, and especially how broken extensions (that needs an update for the new flarum version) would behave, and if they could potentially break flarum completely (Broken database in example.).
I have some ideas on what the update script would look like, but there are many things I need to do first. (Above all, educate myself further on flarum and composer).
I am trying to refactor the install process to use create-project without installing the dependencies, and then install them one by one as to enable installation on more shared hosts as it would limit the memory usage greatly.
This would have to be done before I take on updates.