bug: `'__postgresql_packages' is undefined` on Arch linux.

[Lazerbeak12345]

fatal: [███]: FAILED! => {"changed": false, "msg": "Task failed: Finalization of task args for 'ansible.builtin.set_fact' failed: Error while resolving value 
for 'postgresql_packages': '__postgresql_packages' is undefined"}

I suspect that it is not sourcing vars/Arch.yml for some reason.

[Lazerbeak12345]

As an aside, this was found while I was working on adding support for s6-linux-init downstream:

https://radicle.network/nodes/garden.bastidehub.xyz/rad%3AzD4Ux1XHquWHnw8aJMELSNy8nsFZ/issues/16cf8651e3a563a6e4f210dfcc88cd5bac756e17

(just to show provenance)