Get series from machine

Currently the series when deploying a charm is hardcoded to xenial, when it should be retrieved from the machine.

Change-Id: I2784290dde803e276a77775ee57879897b1c523c
Signed-off-by: David Garcia <david.garcia@canonical.com>
diff --git a/n2vc/n2vc_juju_conn.py b/n2vc/n2vc_juju_conn.py
index 856f79f..0ac8b08 100644
--- a/n2vc/n2vc_juju_conn.py
+++ b/n2vc/n2vc_juju_conn.py
@@ -1113,14 +1113,14 @@
                 )
             )
             self.log.debug("charm: {}".format(charm_path))
-            series = "xenial"
+            machine = model.machines[machine_id]
             # series = None
             application = await model.deploy(
                 entity_url=charm_path,
                 application_name=application_name,
                 channel="stable",
                 num_units=1,
-                series=series,
+                series=machine.series,
                 to=machine_id,
                 config=config,
             )