fix(iot): Fix wrong comparator in monitoring metric

The "low temprature" alert should obviously check for
tempratures BELOW a threshold, not above.

apps/k8s01/iot/monitoring.yaml

@@ -59,7 +59,7 @@ spec:
       annotations:
         description: The temprature of a room/sensor has dropped below 20°C over the past 6 hours.
         summary: The temprature of a room/sensor has dropped below 20°C over the past 6 hours.
-      expr: avg_over_time(shellyht_temperature_celsius[10m]) > 20
+      expr: avg_over_time(shellyht_temperature_celsius[10m]) < 20
       for: 6h
       labels:
         issue: Temprature in {{$labels.name}} is low. Turn up the heating!