Reverted change of unit for Time left sensor.

Changed unit of PM2.5 sensor to be 'ugm3' for
consistency with similar sensors on other devices.

custom_components/tuya_local/devices/breville_smartairconnect_purifier.yaml

@@ -40,7 +40,7 @@ secondary_entities:
         name: sensor
         class: measurement
         type: integer
-        unit: µg/m3
+        unit: ugm3
   - entity: switch
     name: Night mode
     category: config
@@ -92,7 +92,7 @@ secondary_entities:
       - id: 20
         name: sensor
         type: integer
-        unit: d
+        unit: min
   - entity: sensor
     name: Air quality
     class: enum