Fairland pool heatpump: Adjust minimum temperature

Based on the history, the temperature range appears to be simply copied from
the GardenPAC device, which was confirmed to have a minimum of 18.
Adjust the F range as well, rounded (previously it matched 16, probably
copied from before the GardenPAC and not updated when the minimum was set to 18)

Issue #222 (comment)

custom_components/tuya_local/devices/fairland_iphcr15_heatpump.yaml

@@ -49,10 +49,10 @@ primary_entity:
           conditions:
             - dps_val: false
               range:
-                min: 60
+                min: 55
                 max: 115
       range:
-        min: 18
+        min: 12
         max: 45
     - id: 107
       type: integer