go-1.21: Add missing go.env file

[jonjohnsonjr]

See golang/go#57179 for context.

Related: chainguard-images/images#982

[jonjohnsonjr]

2023/07/12 20:14:18 wolfictl update: request query, to check visit https://docs.github.com/en/graphql/overview/explorer: 
query {

  re77145ae45e425c7bbe7b8fe24[9](https://github.com/wolfi-dev/os/actions/runs/5536016421/jobs/10103113605?pr=3566#step:5:10)608204e00e3d82945bae1f8f8a1e3e837293a: repository(owner: "golang", name: "go") {
    nameWithOwner
    refs(refPrefix: "refs/tags/", query: "go1.21", orderBy: {field: TAG_COMMIT_DATE, direction: DESC}, last: [10](https://github.com/wolfi-dev/os/actions/runs/5536016421/jobs/10103113605?pr=3566#step:5:11)0) {
      totalCount
      nodes {
        name
        target {
          commitUrl
        }
      }
    }
  }, 

}
time="2023-07-[12](https://github.com/wolfi-dev/os/actions/runs/5536016421/jobs/10103113605?pr=3566#step:5:13)T20:[14](https://github.com/wolfi-dev/os/actions/runs/5536016421/jobs/10103113605?pr=3566#step:5:15):[18](https://github.com/wolfi-dev/os/actions/runs/5536016421/jobs/10103113605?pr=3566#step:5:19)Z" level=fatal msg="error during command execution: 1 error occurred:\n\t* failed getting github releases: no versions returned from github graphql api\n\n"

Is this meaningful to anyone?