Support alternative operating systems

[schneems]

Expected

When using setup-pack on a mac-os runner, I expect that it will either install the mac OS version of pack or fail.

Actual

Run buildpacks/github-actions/setup-pack@v5.7.1
Run #!/usr/bin/env bash
Installing pack 0.34.2
17s
Run bundle exec rundoc build --path ../tutorials/src/ruby/rundoc.md
== Running your docs
Running: Rundoc.configure do |config|  config.filter_sensitive(
    "tmp/rundoc_screenshots/screenshot_1.png" =>
      "assets/images/ruby-getting-started-screenshot.png"
  )
end
rundoc.require: Start executing "./intro.md"
rundoc.require: Done executing "./intro.md", putting contents into document
rundoc.require: Start executing "../shared/install_pack.md"
Running: $ '(brew install buildpacks/tap/pack) 2>&1'
Running: $ '(pack --version) 2>&1'
bundler: failed to load command: rundoc (/Users/runner/work/rundoc-on-github-actions/rundoc-on-github-actions/.rundoc-workspace/vendor/bundle/ruby/3.3.0/bin/rundoc)
/Users/runner/work/rundoc-on-github-actions/rundoc-on-github-actions/.rundoc-workspace/vendor/bundle/ruby/3.3.0/gems/rundoc-2.0.1/lib/rundoc/code_command/bash.rb:46:in `shell': Command `pack --version` exited with non zero status: sh: /Users/runner/bin/pack: cannot execute binary file (RuntimeError)
	from /Users/runner/work/rundoc-on-github-actions/rundoc-on-github-actions/.rundoc-workspace/vendor/bundle/ruby/3.3.0/gems/rundoc-2.0.1/lib/rundoc/code_command/bash.rb:25:in `call'
	from /Users/runner/work/rundoc-on-github-actions/rundoc-on-github-actions/.rundoc-workspace/vendor/bundle/ruby/3.3.0/gems/rundoc-2.0.1/lib/rundoc/code_section.rb:60:in `block in render'
	from /Users/runner/work/rundoc-on-github-actions/rundoc-on-github-actions/.rundoc-workspace/vendor/bundle/ruby/3.3.0/gems/rundoc-2.0.1/lib/rundoc/code_section.rb:53:in `each'
	from /Users/runner/work/rundoc-on-github-actions/rundoc-on-github-actions/.rundoc-workspace/vendor/bundle/ruby/3.3.0/gems/rundoc-2.0.1/lib/rundoc/code_section.rb:53:in `render'
	from /Users/runner/work/rundoc-on-github-actions/rundoc-on-github-actions/.rundoc-workspace/vendor/bundle/ruby/3.3.0/gems/rundoc-2.0.1/lib/rundoc/parser.rb:26:in `block in to_md'

The setup pack action exits successfully, but later when we try to run pack --version it fails because it's using the linux binary.

Suggested

• Add a pack --version call after install in pack in the existing action to at least fail inside of the same action where the problem exists.

Alternatively:

• Add support for it. It seems that brew is available, it could be effectively what I've got above, call out to brew install.