feat: add cygnet to ports/stm #170

Job	Run time
scheduler	41s
mpy-cross-mac	59s
docs	12m 29s
windows	0s
windows-zephyr	0s
mpy-cross / build (static)	21s
mpy-cross / build (static-aarch64)	1m 57s
tests / run (all)	1m 1s
mpy-cross / build (static-mingw)	47s
tests / run (mpy)	33s
mpy-cross / build (static-raspbian)	41s
tests / run (native)	41s
tests / run (native_mpy)	39s
ports (stm) / board (blues_cygnet)	5m 8s
ports (stm) / board (daisy_seed_with_sdram)	2m 3s
ports (stm) / board (espruino_pico)	1m 32s
ports (stm) / board (espruino_wifi)	1m 50s
ports (stm) / board (feather_stm32f405_express)	2m 12s
ports (stm) / board (meowbit_v121)	3m 18s
ports (stm) / board (nucleo_f446re)	1m 54s
ports (stm) / board (nucleo_f746zg)	2m 8s
ports (stm) / board (nucleo_f767zi)	2m 24s
ports (stm) / board (nucleo_h743zi_2)	2m 9s
ports (stm) / board (openmv_h7)	2m 50s
ports (stm) / board (pyb_nano_v2)	1m 42s
ports (stm) / board (pyboard_v11)	2m 53s
ports (stm) / board (sparkfun_stm32_thing_plus)	2m 9s
ports (stm) / board (sparkfun_stm32f405_micromod)	2m 12s
ports (stm) / board (stm32f411ce_blackpill)	1m 48s
ports (stm) / board (stm32f411ce_blackpill_with_flash)	1m 56s
ports (stm) / board (stm32f411ve_discovery)	3m 41s
ports (stm) / board (stm32f412zg_discovery)	2m 29s
ports (stm) / board (stm32f4_discovery)	2m 16s
ports (stm) / board (stm32f746g_discovery)	2m 21s
ports (stm) / board (swan_r5)	2m 3s
ports (stm) / board (thunderpack_v11)	3m 9s
ports (stm) / board (thunderpack_v12)	5m 4s
	1h 22m 0s

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