Fix series being required for local charms

Local charms may no longer need a series if they are metadata v2
container charms. The Juju CLI uses the model default instead.

Fixes [lp:1929076][]

[lp:1929076]: https://bugs.launchpad.net/juju/+bug/1929076

Author: johnsca

juju/model.py

@@ -1481,6 +1481,9 @@ async def deploy(
                 charm_dir = os.path.abspath(
                     os.path.expanduser(entity_id))
                 series = series or get_charm_series(charm_dir)
+                if not series:
+                    config = await self.get_config()
+                    series = config.get("default-series")
                 if not series:
                     raise JujuError(
                         "Couldn't determine series for charm at {}. "