Exec format error on arm64 based runners

[BenChand]

Hi,

When using an arm64 based runner, I get an exec format error when installing:

install:
  runs-on: runs-on=${{ github.run_id }}/runner=2cpu-linux-arm64
  steps:
    - uses: carvel-dev/setup-action@v2
      with:
        only: imgpkg, kapp, kbld, imgpkg, vendir, ytt
        token: ${{ secrets.token }}
    - shell: bash
      run: |
        imgpkg version
        kapp version
        kbld version
        vendir version
        ytt version

It starts downloading the amd64 releases:

Installing imgpkg:latest, kapp:latest, kbld:latest, imgpkg:latest, vendir:latest, ytt:latest
Downloading ytt v0.52.0 from https://github.com/carvel-dev/ytt/releases/download/v0.52.0/ytt-linux-amd64
Downloading kbld v0.46.0 from https://github.com/carvel-dev/kbld/releases/download/v0.46.0/kbld-linux-amd64
Downloading imgpkg v0.46.1 from https://github.com/carvel-dev/imgpkg/releases/download/v0.46.1/imgpkg-linux-amd64
Downloading kapp v0.64.2 from https://github.com/carvel-dev/kapp/releases/download/v0.64.2/kapp-linux-amd64
Downloading imgpkg v0.46.1 from https://github.com/carvel-dev/imgpkg/releases/download/v0.46.1/imgpkg-linux-amd64
Downloading vendir v0.44.0 from https://github.com/carvel-dev/vendir/releases/download/v0.44.0/vendir-linux-amd64
✅  Verified checksum: "90e8d123d5e33ab13b849997bdb05626fa7f2384120d87a29eebd56490105ca9  ./kbld-linux-amd64"
✅  Verified checksum: "4c222403a9a2d54d8bb0e0ca46f699ee4040a2bddd5ab3b6354efd2c85d3209f  ./ytt-linux-amd64"
✅  Verified checksum: "1bc6b735dbdd940a5c78661781f937090bd5fbc89172f01e600ee91fe122edbe  ./imgpkg-linux-amd64"
✅  Verified checksum: "1bc6b735dbdd940a5c78661781f937090bd5fbc89172f01e600ee91fe122edbe  ./imgpkg-linux-amd64"
✅  Verified checksum: "a2befbb9dd4f174aac7a34fe0bd50b1e5dc356dadaed0183a24b817f2fd1d094  ./vendir-linux-amd64"

/opt/hostedtoolcache/imgpkg/0.46.1/arm64/imgpkg: cannot execute binary file: Exec format error

Would be great if it could auto-detect the architecture and download the appropriate binary. Or allow us to specify arm64