feat: add cygnet to ports/stm #160

Job	Run time
scheduler	41s
docs	14m 39s
mpy-cross-mac	1m 0s
windows	0s
windows-zephyr	0s
tests / run (all)	1m 2s
tests / run (mpy)	34s
tests / run (native)	44s
tests / run (native_mpy)	40s
mpy-cross / build (static)	15s
mpy-cross / build (static-aarch64)	51s
mpy-cross / build (static-mingw)	52s
mpy-cross / build (static-raspbian)	54s
ports (stm) / board (cygnet)	2m 41s
ports (stm) / board (daisy_seed_with_sdram)	3m 8s
ports (stm) / board (espruino_pico)	2m 18s
ports (stm) / board (espruino_wifi)	2m 50s
ports (stm) / board (feather_stm32f405_express)	3m 11s
ports (stm) / board (meowbit_v121)	2m 36s
ports (stm) / board (nucleo_f446re)	1m 57s
ports (stm) / board (nucleo_f746zg)	2m 41s
ports (stm) / board (nucleo_f767zi)	2m 43s
ports (stm) / board (nucleo_h743zi_2)	3m 6s
ports (stm) / board (openmv_h7)	2m 53s
ports (stm) / board (pyb_nano_v2)	2m 30s
ports (stm) / board (pyboard_v11)	3m 4s
ports (stm) / board (sparkfun_stm32_thing_plus)	3m 24s
ports (stm) / board (sparkfun_stm32f405_micromod)	3m 40s
ports (stm) / board (stm32f411ce_blackpill)	2m 44s
ports (stm) / board (stm32f411ce_blackpill_with_flash)	2m 22s
ports (stm) / board (stm32f411ve_discovery)	2m 39s
ports (stm) / board (stm32f412zg_discovery)	3m 20s
ports (stm) / board (stm32f4_discovery)	3m 1s
ports (stm) / board (stm32f746g_discovery)	2m 39s
ports (stm) / board (swan_r5)	2m 52s
ports (stm) / board (thunderpack_v11)	2m 53s
ports (stm) / board (thunderpack_v12)	2m 36s
	1h 30m 0s

Provide feedback