MQTT publish API changes

In the future, the MQTT publish API will require explicit values for qos and retain. Passing None for either argument will no longer be supported. Custom integrations should update their code to accept the defaults, or pass valid typed arguments. The fallbacks of None to a valid value for qos and retain will stop working with HA Core 2027.6.

The new API signatures are:

def publish(
    hass: HomeAssistant,
    topic: str,
    payload: PublishPayloadType,
    qos: int = 0,
    retain: bool = False,
    encoding: str | None = DEFAULT_ENCODING,
) -> None:
    """Publish message to a MQTT topic."""
    hass.create_task(async_publish(hass, topic, payload, qos, retain, encoding))

and

async def async_publish(
    hass: HomeAssistant,
    topic: str,
    payload: PublishPayloadType,
    qos: int = 0,
    retain: bool = False,
    encoding: str | None = DEFAULT_ENCODING,
) -> None:
    """Publish message to a MQTT topic."""