feat: add cygnet to ports/stm #164

Job	Run time
scheduler	52s
mpy-cross-mac	1m 3s
docs	13m 58s
windows	0s
windows-zephyr	0s
mpy-cross / build (static)	24s
mpy-cross / build (static-aarch64)	40s
mpy-cross / build (static-mingw)	44s
mpy-cross / build (static-raspbian)	40s
tests / run (all)	56s
tests / run (mpy)	39s
tests / run (native)	50s
tests / run (native_mpy)	41s
ports (stm) / board (cygnet)	5m 27s
ports (stm) / board (daisy_seed_with_sdram)	2m 3s
ports (stm) / board (espruino_pico)	1m 49s
ports (stm) / board (espruino_wifi)	1m 53s
ports (stm) / board (feather_stm32f405_express)	2m 33s
ports (stm) / board (meowbit_v121)	3m 8s
ports (stm) / board (nucleo_f446re)	2m 3s
ports (stm) / board (nucleo_f746zg)	1m 57s
ports (stm) / board (nucleo_f767zi)	1m 55s
ports (stm) / board (nucleo_h743zi_2)	2m 1s
ports (stm) / board (openmv_h7)	2m 34s
ports (stm) / board (pyb_nano_v2)	2m 10s
ports (stm) / board (pyboard_v11)	2m 32s
ports (stm) / board (sparkfun_stm32_thing_plus)	2m 31s
ports (stm) / board (sparkfun_stm32f405_micromod)	2m 39s
ports (stm) / board (stm32f411ce_blackpill)	1m 52s
ports (stm) / board (stm32f411ce_blackpill_with_flash)	1m 48s
ports (stm) / board (stm32f411ve_discovery)	4m 10s
ports (stm) / board (stm32f412zg_discovery)	2m 3s
ports (stm) / board (stm32f4_discovery)	2m 34s
ports (stm) / board (stm32f746g_discovery)	2m 31s
ports (stm) / board (swan_r5)	2m 32s
ports (stm) / board (thunderpack_v11)	3m 27s
ports (stm) / board (thunderpack_v12)	5m 25s
	1h 25m 4s

Provide feedback