Add support for arm64 in Docker image

[marfier]

Is your feature request related to a problem? Please describe.
I can't run the openbullet/openbullet2 image on my Raspberry Pi 4 because it only supports amd64.

Describe the solution you'd like
Add arm64 compatibility in the openbullet/openbullet2 image.

Describe alternatives you've considered
I couldn't compile as directed in the forum page for the same reason.

[openbullet]

Done in 9db9f8b you should be able to use the image on your rpi4 starting from update 0.1.7

[marfier]

I am still getting the same issue, even on 0.1.7:

ubuntu@ubuntu:~$ sudo docker run --name openbullet2 --rm -p 8069:5000 -v UserData:/app/UserData -it openbullet/openbullet2:latest
sudo: unable to resolve host ubuntu: Name or service not knownWARNING: The requested image's platform (linux/amd64) does not match the detected host platform (linux/arm64/v8) and no specific platform was requested
standard_init_linux.go:219: exec user process caused: exec format error
ubuntu@ubuntu:~$

It seems like linux/arm64 is now supported, but not linux/arm64/v8.

[openbullet]

Alright thank you for the feedback, @meinname will take a look tomorrow

[meinname]

It seems docker has some problems to use the right architecture:
docker/for-linux#1170 (comment)

So let's approach it from both directions:
I set it now to explicitly to linux/arm64/v8 instead of just linux/arm64 and i moved the arm builds to top of the list e0261eb
So hopefully on 0.1.8 it will be no problem anymore.

And in the meantime you can see if it is fixed with the latest docker version.

[openbullet]

@GalacticLion7 0.1.8 is live, please test