Add device classes new in HA 2021.9 (#2248)

esphome/components/senseair/sensor.py

@@ -7,6 +7,7 @@ from esphome.const import (
     CONF_CO2,
     CONF_ID,
     ICON_MOLECULE_CO2,
+    DEVICE_CLASS_CARBON_DIOXIDE,
     STATE_CLASS_MEASUREMENT,
     UNIT_PARTS_PER_MILLION,
 )
@@ -41,6 +42,7 @@ CONFIG_SCHEMA = (
                 unit_of_measurement=UNIT_PARTS_PER_MILLION,
                 icon=ICON_MOLECULE_CO2,
                 accuracy_decimals=0,
+                device_class=DEVICE_CLASS_CARBON_DIOXIDE,
                 state_class=STATE_CLASS_MEASUREMENT,
             ),
         }