The charm-helpers fix [1] ensures that the new local_address function in
charm-helpers works with pre-2.8 Juju. This rebuild is to pick that
change for the 21.01 charm freeze testing period.
[1]: https://github.com/juju/charm-helpers/pull/562
Change-Id: I36397564b538524934b9c59ad88818182f0e72a0