Add Entity categories for Home Assistant (#2636)

esphome/components/xiaomi_mjyd02yla/binary_sensor.py

@@ -10,6 +10,7 @@ from esphome.const import (
     CONF_BATTERY_LEVEL,
     DEVICE_CLASS_BATTERY,
     DEVICE_CLASS_ILLUMINANCE,
+    ENTITY_CATEGORY_DIAGNOSTIC,
     STATE_CLASS_MEASUREMENT,
     STATE_CLASS_NONE,
     UNIT_PERCENT,
@@ -51,6 +52,7 @@ CONFIG_SCHEMA = cv.All(
                 accuracy_decimals=0,
                 device_class=DEVICE_CLASS_BATTERY,
                 state_class=STATE_CLASS_MEASUREMENT,
+                entity_category=ENTITY_CATEGORY_DIAGNOSTIC,
             ),
             cv.Optional(CONF_ILLUMINANCE): sensor.sensor_schema(
                 unit_of_measurement=UNIT_LUX,