ci: check that files generated by boards.txt.py are up to date
ci: check that files generated by boards.txt.py are up to date

Files are re-generated in CI build, and git diff is used to check if
there have been any changes.

sticilface/Arduino,Adam5Wu/Arduino,sticilface/Arduino,hallard/Arduino,Adam5Wu/Arduino,Lan-Hekary/Arduino,wemos/Arduino,esp8266/Arduino,esp8266/Arduino,lrmoreno007/Arduino,hallard/Arduino,hallard/Arduino,wemos/Arduino,Lan-Hekary/Arduino,esp8266/Arduino,Adam5Wu/Arduino,Lan-Hekary/Arduino,esp8266/Arduino,hallard/Arduino,lrmoreno007/Arduino,lrmoreno007/Arduino,wemos/Arduino,wemos/Arduino,wemos/Arduino,sticilface/Arduino,lrmoreno007/Arduino,esp8266/Arduino,sticilface/Arduino,Adam5Wu/Arduino,hallard/Arduino,Adam5Wu/Arduino,lrmoreno007/Arduino,sticilface/Arduino,Lan-Hekary/Arduino,Lan-Hekary/Arduino