Running on Micropython

[FlorianLudwig]

@garykuipers is running aMQTT on MicroPython. This is a really cool use-case! (btw @garykuipers would love to hear more about your exact use-case.)

We should investigate if we want to support that use case, e.g. check if we can create a ci pipeline to check if aMQTT runs on MicroPython. At least the client part of aMQTT would be great to officially support.