Inkbird ITC-306A: remove units from calibration offset.

Since this is a relative temperature offset, not an absolute temperature, we don't want HomeAssistant doing conversion on the values when the unit setting does not match the HomeAssistant settings.

custom_components/tuya_local/devices/inkbird_itc306a_thermostat.yaml

@@ -138,10 +138,6 @@ secondary_entities:
                 range:
                   min: -150
                   max: 150
-      - id: 101
-        name: unit
-        type: string
-        hidden: true
   - entity: number
     name: Continuous Heat Hours
     icon: "mdi:clock"

tests/devices/test_inkbird_itc306a_thermostat.py

@@ -100,7 +100,6 @@ class TestInkbirdThermostat(
                     "step": 0.1,
                     "min": -9.9,
                     "max": 9.9,
-                    "unit": TEMP_CELSIUS,
                 },
                 {
                     "name": "number_continuous_heat_hours",