apt upgrade can fail if unattended upgrades are in process

[Apreche]

If the deployment playbook unluckily fires at the same time that the system's unattended upgrades are in process, the entire playbook will fail on that task because of contention for the dpkg lock.

Find some sort of solution for this so the playbook never errors. We can probably just skip the apt upgrade step if this is happening.

However, for other tasks, like installing PostgreSQL, we can't just skip if it is not already installed. We'll need some sort of clever wait/retry? At the very least we can tell the user to wait a bit, then press the retry button on their Github Action.