Storage feature prevents from deploying into a LXD container

[nobuto-m]

$ juju version
2.9.42-ubuntu-amd64

$ juju deploy --series jammy ubuntu
Located charm "ubuntu" in charm-hub, revision 22
Deploying "ubuntu" from charm-hub charm "ubuntu", revision 22 in channel stable on jammy

$ juju add-unit ubuntu --to lxd:0
ERROR acquiring machine to host unit "ubuntu/1": cannot assign unit "ubuntu/1" to machine 0/lxd/0: adding storage to lxd container not supported (not supported)

Originally posted by @nobuto-m in #35 (comment)

[addyess]

a new charm is in latest/candidate but there are issues when upgrading from an existing latest/stable charm

❯ juju refresh ubuntu --channel=latest/candidate 
Added charm-hub charm "ubuntu", revision 23 in channel latest/candidate, to the model
ERROR updating charm config: cannot upgrade application "ubuntu" to charm "ch:amd64/focal/ubuntu-23": existing storage "files" with location changed from single to multiple

[addyess]

Fresh installs however work just fine

❯ juju deploy ubuntu --channel=candidate ubuntu2
Located charm "ubuntu" in charm-hub, revision 23
Deploying "ubuntu2" from charm-hub charm "ubuntu", revision 23 in channel candidate on ubuntu@22.04/stable
❯ juju add-unit ubuntu2 --to lxd:0

[addyess]

Addressing this concerns with #51