Build arm64 Docker image

[felixvanoost]

Builds and tests a multi-architecture Docker image for both linux/amd64 and linux/arm64 platforms as discussed in this comment and in #114. This allows ARM-based machines to run the image natively with no emulation.

This includes the following changes:

• Builds the linux/amd64 and linux/arm64 images on dedicated native runners. The typical "low-effort" QEMU-based approach to building multi-arch images is not possible in this case due to memory constraints with the free GitHub runners, so the changes in this PR rely on a 3rd-party integration with BuildJet to provide the native arm64 runner. BuildJet provides $5 of free runner time to get started, which equates to $5 / $0.008 = 625 minutes total with the runner I chose (see pricing info). Each build takes about 15 minutes, so I don't anticipate this project needing to spend any money whatsoever on this for the forseeable future. They also didn't collect credit card information from me when I signed up, so there's no danger of being accidentally charged.
• Tests the image using the examples/nfldb.er diagram and stores the resulting PNG as an artifact for review.
• Switches the base image to haskell:8-slim, which is about half the size of haskell:8 (341MB vs 635MB).

I appreciate that this reliance on a 3rd party is far from optimal and fully understand if the decision is made to reject this PR. The only two other viable approaches to build multi-archecture binaries would be to:

• Set up a self-hosted arm64 runner.
• Set up a GHC cross-compiler and run everything on the free GitHub amd64 runners. This is apparently quite complex to do with Haskell and beyond the effort I'm willing to contribute.

Closes #40
Closes #114

[felixvanoost]

@mmzx mentioning you in case GitHub doesn't send notifications for PRs. 😅

[mmzx]

I think we can do this! Thank you!

[felixvanoost]

@mmzx Any idea when the next Erd release might be available to include these changes? I'm just looking for a rough idea when I can start integrating this in downstream projects. ✌🏻

[felixvanoost]

@mmzx I noticed the CI build job failed after merging these changes. Adding this step at the beginning of the workflow should resolve the repository naming issue seen here:

- name: Make the image name lowercase
  run: |
    echo "IMAGE_NAME_LOWERCASE=${IMAGE_NAME,,}" >>${GITHUB_ENV}
  env:
    IMAGE_NAME: '${{ github.repository }}'

And then use IMAGE_NAME_LOWERCASE instead of IMAGE_NAME in the rest of the workflow. I can test these changes locally and submit another PR, but it's difficult to validate without directly testing in this repo. The solution above is taken from another GitHub discussion.

For the other job that failed on the BuildJet runner, you'll have to set up BuildJet on your account here. If this is an issue because @BurntSushi is the repo owner and it can only be done by him, I may have to build and publish the images in my fork instead.

[felixvanoost]

Hey @mmzx, is this still something you'd be willing to look into?