Ugh... not able to fetch new commits about mina

[tvcam]

Set execution_mode to :system fixs this:
set :execution_mode, :system

ref: https://github.com/mina-deploy/mina/blob/master/docs/how_mina_works.md#execution-modes-runners

[lovro-bikic]

This is a result of GitHub changing its SSH host key (https://github.blog/2023-03-23-we-updated-our-rsa-ssh-host-key).

You can resolve this by SSH-ing to the server (you can do it via Mina with the command mina ssh) and replacing the host key in the known_hosts file, which is explained in this part of the blog post.