Move to `rppal`?

Seems that [`sysfs_gpio`][sysfs_gpio] is no longer actively maintained, and [`rppal`][rppal] seems the perfect alternative for Raspberry Pi. Not only that, it will be faster and should be more integrated. There has not been a lot of development in that area in the last times, though. Should we move?

[sysfs_gpio]: https://crates.io/crates/sysfs_gpio
[rppal]: https://crates.io/crates/rppal