Add target_humidity_step attribute to humidifier (#156906)

Co-authored-by: yunseon.park <yunseon.park@lge.com>

tests/components/google_assistant/test_google_assistant.py

@@ -354,7 +354,7 @@ async def test_query_humidifier_request(
     assert devices["humidifier.humidifier"] == {
         "on": True,
         "online": True,
-        "humiditySetpointPercent": 68,
+        "humiditySetpointPercent": 65,
         "humidityAmbientPercent": 45,
     }
     assert devices["humidifier.dehumidifier"] == {

tests/components/humidifier/test_recorder.py

@@ -9,6 +9,7 @@ from homeassistant.components.humidifier import (
     ATTR_AVAILABLE_MODES,
     ATTR_MAX_HUMIDITY,
     ATTR_MIN_HUMIDITY,
+    ATTR_TARGET_HUMIDITY_STEP,
 )
 from homeassistant.components.recorder import Recorder
 from homeassistant.components.recorder.history import get_significant_states
@@ -46,3 +47,4 @@ async def test_exclude_attributes(recorder_mock: Recorder, hass: HomeAssistant)
         assert ATTR_MAX_HUMIDITY not in state.attributes
         assert ATTR_AVAILABLE_MODES not in state.attributes
         assert ATTR_FRIENDLY_NAME in state.attributes
+        assert ATTR_TARGET_HUMIDITY_STEP not in state.attributes