MQTT Availability will now be posted with retain flag, to ensure HA s…

…till sees the device after a restart or upgrade.

evseMQTT/mqttclient.py

@@ -52,7 +52,7 @@ def publish(self, topic, payload, qos=0, retain=False):
         self.client.publish(topic, payload, qos, retain)
 
     def publish_availability(self, identifier, state):
-        self.client.publish(f"evseMQTT/{identifier}/availability", state)
+        self.client.publish(f"evseMQTT/{identifier}/availability", state, 0, True)
 
     def publish_state(self, identifier, topic, state):
         self.client.publish(f"evseMQTT/{identifier}/state/{topic}", json.dumps(state))