Improve type hint in entity_component (#80596)

Imrpove type hint in entity_component

homeassistant/helpers/entity_component.py

@@ -37,6 +37,7 @@ _EntityT = TypeVar("_EntityT", bound=entity.Entity)
 async def async_update_entity(hass: HomeAssistant, entity_id: str) -> None:
     """Trigger an update for an entity."""
     domain = entity_id.split(".", 1)[0]
+    entity_comp: EntityComponent[entity.Entity] | None
     entity_comp = hass.data.get(DATA_INSTANCES, {}).get(domain)
 
     if entity_comp is None: