Fix for Multicast to level 4 #99

Job	Run time
build (adafruit_feather_rp2040) / build	59s
build (adafruit_itsybitsy_rp2040) / build	1m 22s
build (adafruit_qtpy_rp2040) / build	1m 36s
build (pico) / build	1m 16s
build (arduino_nano_rp2040_connect) / build	1m 3s
build (pimoroni_pga2040) / build	1m 15s
build (pimoroni_picolipo_16mb) / build	1m 6s
build (pimoroni_picolipo_4mb) / build	1m 18s
build (pimoroni_tiny2040) / build	1m 25s
build (sparkfun_micromod) / build	1m 4s
build (sparkfun_promicro) / build	1m 2s
build (sparkfun_thingplus) / build	56s
	14m 22s

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