Add ARM64 support for Docker image

[dlackty]

Feature Request

ARM64 runners are now officially supported by GitHub Actions. The current Docker image only supports linux/amd64, which causes warnings when running on ARM64 runners:

WARNING: The requested image's platform (linux/amd64) does not match the detected host platform (linux/arm64/v8) and no specific platform was requested

Proposed Solution

Add multi-platform support to the Docker image build by updating .github/workflows/release-build.yml to include ARM64:

- name: Build + Push Docker image
  id: build-and-push
  uses: docker/build-push-action@c56af957549030174b10d6867f20e78cfd7debc5
  with:
    context: .
    push: true
    tags: ${{ steps.meta.outputs.tags }}
    labels: ${{ steps.meta.outputs.labels }}
    platforms: linux/amd64,linux/arm64  # Add this line

The base .NET images (mcr.microsoft.com/dotnet/sdk:6.0 and mcr.microsoft.com/dotnet/runtime:6.0) already support ARM64, so this should work without additional changes.

Related Issues

• ARM64 not supported #342 (closed as stale)
• Running on ARM64 fails #60 (closed)
• Add configuration to build container image for ARM64 #193 (PR closed without merge)