[RFC] RISC-V support

[stintel]

This PR updates the Alpine base container to Alpine 3.20, which supports the RISC-V architecture, and enables 64-bit RISC-V builds in Github actions.

I understand this probably won't be merged soon, due to the Alpine bump and the potential for regressions, but like this people who have RISC-V hardware lying around, can give it a try. I'm personally running a locally built zigbee2mqtt container on the VisionFive 2 for the past week and it's been working rather well.

[Koenkk]

Does it also work with Alpine 3.18? We currently cannot migrate to 3.20 since this makes the Docker build hang.

[stintel]

Does it also work with Alpine 3.18?

It does not, Alpine 3.20 is the first version that supports the RISC-V architecture.

[Koenkk]

Then I will hold this until the bug in Node 20 is fixed (Alpine 3.18 is the last to use Node 18 which doesnt have this bug)

[stintel]

Understood! Out of curiosity, is there any issue for that bug in Node 20? Also, interestingly enough, CI for this PR succeeded, while it previously hung in my fork and was terminated after 360 minutes.

[Koenkk]

Ci succeeds because it doesnt build the container (which is what fails for armv7 and 6 platforms on node 20)

[Nerivec]

serialport currently does not provide support for riscv64.
https://serialport.io/docs/guide-platform-support#supported-platforms-and-architectures

[Koenkk]

riscv is not officially supported by serialport so we cannot guarantee it works. @stintel could you do a check with the latest-dev image?

[stintel]

@Koenkk had to add adapter: zstack to configuration.yaml but seems to be working fine now. This is awesome, thank you!