Add microzig.config.board_name #177

Job	Run time
Check that stm32 generated code is up to date	45s
Unit Test UF2 (ubuntu-latest)	19s
Build (ubuntu-latest)	31s
Unit Test UF2 (windows-latest)	59s
Build (windows-latest)	1m 7s
Unit Test UF2 (macos-latest)	23s
Build (macos-latest)	30s
Build Website	20s
Build Examples (espressif/esp)	2m 8s
Dry Run Packaging	1m 21s
Build Examples (gigadevice/gd32)	2m 16s
Unit Test Ports (ubuntu-latest, gigadevice/gd32)	21s
Build Examples (microchip/avr)	2m 10s
Unit Test Regz (ubuntu-latest)	25s
Unit Test Ports (ubuntu-latest, raspberrypi/rp2xxx)	16s
Build Examples (microchip/atsam)	1m 58s
Unit Test Regz (windows-latest)	1m 23s
Unit Test Ports (ubuntu-latest, stmicro/stm32)	22s
Build Examples (nordic/nrf5x)	1m 58s
Unit Test Ports (windows-latest, gigadevice/gd32)	55s
Unit Test Regz (macos-latest)	28s
Build Examples (nxp/lpc)	2m 4s
Unit Test Ports (windows-latest, raspberrypi/rp2xxx)	1m 7s
Build Examples (stmicro/stm32)	29s
Unit Test Ports (windows-latest, stmicro/stm32)	1m 42s
Build Examples (raspberrypi/rp2xxx)	2m 31s
Unit Test Ports (macos-latest, gigadevice/gd32)	25s
Build Examples (wch/ch32v)	2m 15s
Unit Test Ports (macos-latest, raspberrypi/rp2xxx)	45s
Unit Test Ports (macos-latest, stmicro/stm32)	23s
	32m 36s

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