Pass correct charm url to series selector

Fixes #925

Currently we seem to be passing to the series selector the default url
for the charm (e.g. `ch:zinc-k8s`), instead of the url returned from
the ResolveCharms facade call (e.g. `ch:amd64/jammy/zinc-k8s-117`). As
a result we're sending the wrong url (e.g., in #925
`ch:amd64/focal/zinc-k8s-117`) to the `AddPendingResources`, which
results in the wrong image to be selected for the resources for the
charm (e.g., in #925 the incorrect oci-image for the zinc-k8s charm).

Author: cderici

juju/model.py

@@ -1897,7 +1897,7 @@ async def _resolve_charm(self, url, origin, force=False, series=None, model_conf
         charm_url = URL.parse(result.url)
 
         # run the series selector to get a series for the base
-        selected_series = utils.series_selector(series, url, model_config, supported_series, force)
+        selected_series = utils.series_selector(series, charm_url, model_config, supported_series, force)
         result.charm_origin.base = utils.get_base_from_origin_or_channel(resolved_origin, selected_series)
         charm_url.series = selected_series