Migrate backported StrEnum to built-in StrEnum (#97101)

homeassistant/helpers/selector.py

@@ -2,14 +2,13 @@
 from __future__ import annotations
 
 from collections.abc import Callable, Mapping, Sequence
-from enum import IntFlag
+from enum import IntFlag, StrEnum
 from functools import cache
 from typing import Any, Generic, Literal, Required, TypedDict, TypeVar, cast
 from uuid import UUID
 
 import voluptuous as vol
 
-from homeassistant.backports.enum import StrEnum
 from homeassistant.const import CONF_MODE, CONF_UNIT_OF_MEASUREMENT
 from homeassistant.core import split_entity_id, valid_entity_id
 from homeassistant.util import decorator