Add support for Raspberry Pi 5

[SiboVG]

Today I wanted to test out my TMC2209 driver code on a RPi 5, only to find out that RPi.GPIO does not support the new RPi GPIO hardware.

I would therefore propose to either replace RPi.GPIO entirely with the gpiozero library, or to provide some sort of flag that can switch between RPi.GPIO (since a lot of users still use this library) and gpiozero (for RPi 5 users). I guess the latter is more flexible for users, but more tricky to implement.

Reason for choosing gpiozero: it is more high-level than for instance gpiod, but still supports pretty much all the functions that RPi.GPIO has.