fix(saswell_t29utk_thermostat): temp unit from device is lowercase

Issue #5081, logs from #45 also agree, the device info there came from
Query Device Properties, which generally returns cloud rather than
local details.

custom_components/tuya_local/devices/saswell_t29utk_thermostat.yaml

@@ -18,7 +18,7 @@ entities:
             step: 5
             constraint: temperature_unit
             conditions:
-              - dps_val: "F"
+              - dps_val: f
                 step: 10
                 range:
                   min: 410
@@ -61,10 +61,9 @@ entities:
         name: temperature_unit
         type: string
         mapping:
-          - dps_val: F
+          - dps_val: f
             value: F
-          - dps_val: C
-            value: C
+          - value: C
       - id: 101
         name: preset_mode
         type: boolean
@@ -135,9 +134,9 @@ entities:
         name: option
         type: string
         mapping:
-          - dps_val: F
+          - dps_val: f
             value: fahrenheit
-          - dps_val: C
+          - dps_val: c
             value: celsius
   - entity: select
     name: Configuration