feat: add cygnet to ports/stm #168

Job	Run time
scheduler	50s
mpy-cross-mac	1m 6s
docs	13m 46s
windows	0s
windows-zephyr	0s
tests / run (all)	56s
tests / run (mpy)	33s
tests / run (native)	42s
tests / run (native_mpy)	35s
mpy-cross / build (static)	16s
mpy-cross / build (static-aarch64)	37s
mpy-cross / build (static-mingw)	42s
mpy-cross / build (static-raspbian)	50s
ports (stm) / board (cygnet)	5m 9s
ports (stm) / board (daisy_seed_with_sdram)	2m 1s
ports (stm) / board (espruino_pico)	1m 32s
ports (stm) / board (espruino_wifi)	1m 50s
ports (stm) / board (feather_stm32f405_express)	2m 6s
ports (stm) / board (meowbit_v121)	3m 39s
ports (stm) / board (nucleo_f446re)	1m 52s
ports (stm) / board (nucleo_f746zg)	2m 12s
ports (stm) / board (nucleo_f767zi)	2m 20s
ports (stm) / board (nucleo_h743zi_2)	2m 3s
ports (stm) / board (openmv_h7)	2m 11s
ports (stm) / board (pyb_nano_v2)	1m 39s
ports (stm) / board (pyboard_v11)	2m 8s
ports (stm) / board (sparkfun_stm32_thing_plus)	2m 16s
ports (stm) / board (sparkfun_stm32f405_micromod)	2m 34s
ports (stm) / board (stm32f411ce_blackpill)	2m 14s
ports (stm) / board (stm32f411ce_blackpill_with_flash)	1m 50s
ports (stm) / board (stm32f411ve_discovery)	3m 51s
ports (stm) / board (stm32f412zg_discovery)	2m 22s
ports (stm) / board (stm32f4_discovery)	2m 3s
ports (stm) / board (stm32f746g_discovery)	2m 13s
ports (stm) / board (swan_r5)	2m 9s
ports (stm) / board (thunderpack_v11)	3m 24s
ports (stm) / board (thunderpack_v12)	5m 21s
	1h 21m 52s

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