Use uptime device_class for Uptime sensor (#169692)

homeassistant/components/uptime/sensor.py

@@ -24,7 +24,7 @@ async def async_setup_entry(
 class UptimeSensor(SensorEntity):
     """Representation of an uptime sensor."""
 
-    _attr_device_class = SensorDeviceClass.TIMESTAMP
+    _attr_device_class = SensorDeviceClass.UPTIME
     _attr_has_entity_name = True
     _attr_name = None
     _attr_should_poll = False

tests/components/uptime/snapshots/test_sensor.ambr

@@ -2,7 +2,7 @@
 # name: test_uptime_sensor
   StateSnapshot({
     'attributes': ReadOnlyDict({
-      'device_class': 'timestamp',
+      'device_class': 'uptime',
       'friendly_name': 'Uptime',
     }),
     'context': <ANY>,
@@ -38,7 +38,7 @@
     'object_id_base': None,
     'options': dict({
     }),
-    'original_device_class': <SensorDeviceClass.TIMESTAMP: 'timestamp'>,
+    'original_device_class': <SensorDeviceClass.UPTIME: 'uptime'>,
     'original_icon': None,
     'original_name': None,
     'platform': 'uptime',