ARM64 Support

[gjrtimmer]

I'm unable to build this image with docker buildx for amd64 and arm64.

What I'm working on now, is to update the BUILDPLATOFRM variable, this should be updated to TARGETPLATFORM when using buildx with qemu.

[gjrtimmer]

Furthermore, the base alpine 3.19 image might need to be replaced because it complains about the following error even while the image is being build for arm64.

Status: Downloaded newer image for harbor.local/gitlab/oss/gitlab-merger-bot:arm64
x86_64-binfmt-P: Could not open '/lib/ld-musl-x86_64.so.1': No such file or directory

[pepakriz]

I'm not sure what to suggest. Both image variants are successfully built in github actions. I tried to build amd64 locally without any problem (but without qemu).

[gjrtimmer]

And the arm64 is running succesfull?