Set version to 3.0.0_alpha
Let pmbootstrap display 3.0.0_alpha on crash, so it's clear when people
are using the new codebase.
Before you report this error, ensure that pmbootstrap is up to date.
Find the latest version here: https://gitlab.postmarketos.org/postmarketos/pmbootstrap/-/tags
Your version: 3.0.0_alpha