Avoid creating a task on callback in owntracks when using mqtt (#90548)

Nothing was being awaited in the callback. It did not
need to be a coro

homeassistant/components/owntracks/__init__.py

@@ -24,6 +24,7 @@ from homeassistant.helpers.dispatcher import (
 )
 from homeassistant.helpers.typing import ConfigType
 from homeassistant.setup import async_when_setup
+from homeassistant.util.json import json_loads
 
 from .config_flow import CONF_SECRET
 from .const import DOMAIN
@@ -133,10 +134,11 @@ async def async_connect_mqtt(hass, component):
     """Subscribe to MQTT topic."""
     context = hass.data[DOMAIN]["context"]
 
-    async def async_handle_mqtt_message(msg):
+    @callback
+    def async_handle_mqtt_message(msg):
         """Handle incoming OwnTracks message."""
         try:
-            message = json.loads(msg.payload)
+            message = json_loads(msg.payload)
         except ValueError:
             # If invalid JSON
             _LOGGER.error("Unable to parse payload as JSON: %s", msg.payload)