occasional weirdness with not connecting over stdio USB when calling getchar and sscanf

[kilograham]

see #575 and https://forums.raspberrypi.com/viewtopic.php?f=145&t=321326

[lurch]

Just having read that forum thread and #575 again, is it possible that some USB hosts are just "slow" to enumerate, and so the increased sleep-time in #575 gives these "slow" USB ports an increased chance of being able to enumerate the Pico in time? 🤷 (that's just a random guess, I know very little about USB)

Any thoughts from @P33M ? (who I believe has intimate knowledge of the Linux USB drivers)

[kilograham]

likely fixed by #918

[kilograham]

closing due to #918 being merged into develop