Arm64 support

[RichardoC]

Could you officially support ARM64 as well as AMD64?

This PR is currently working with the following exceptions

└─$ plz build //...                                                           
Build stopped after 1.49s. 2 targets failed:
    //examples/pipelines/scorecard-project/pipelinerun:pipelinerun
Error building target //examples/pipelines/scorecard-project/pipelinerun:pipelinerun: exit status 1
'GITHUB_TOKEN' is not set.

    //third_party/binary/tatskaari/go-deps:go-deps
1 error occurred:
        * Error retrieving https://github.com/Tatskaari/go-deps/releases/download/v1.4.2/go_deps_v1.4.2_linux_arm64: 404 Not Found

scorecard is because I don't have the required Github token and go-deps does not support ARM64 yet, though there is an issue for it

I've not made the changes to enable ARM64 packages to be created, but think that would be the next step if you want to support this arch.

Thanks!

[northdpole]

we don't use please anymore, closing as go natively supports arm now