Use SensorDeviceClass in gtfs (#61657)

Co-authored-by: epenet <epenet@users.noreply.github.com>

homeassistant/components/gtfs/sensor.py

@@ -14,15 +14,10 @@ import voluptuous as vol
 
 from homeassistant.components.sensor import (
     PLATFORM_SCHEMA as SENSOR_PLATFORM_SCHEMA,
+    SensorDeviceClass,
     SensorEntity,
 )
-from homeassistant.const import (
-    ATTR_ATTRIBUTION,
-    CONF_NAME,
-    CONF_OFFSET,
-    DEVICE_CLASS_TIMESTAMP,
-    STATE_UNKNOWN,
-)
+from homeassistant.const import ATTR_ATTRIBUTION, CONF_NAME, CONF_OFFSET, STATE_UNKNOWN
 from homeassistant.core import HomeAssistant
 import homeassistant.helpers.config_validation as cv
 from homeassistant.helpers.typing import ConfigType, DiscoveryInfoType
@@ -522,7 +517,7 @@ def setup_platform(
 class GTFSDepartureSensor(SensorEntity):
     """Implementation of a GTFS departure sensor."""
 
-    _attr_device_class = DEVICE_CLASS_TIMESTAMP
+    _attr_device_class = SensorDeviceClass.TIMESTAMP
 
     def __init__(
         self,