ci(release): set GH_TOKEN when creating GitHub release

[merceyz]

What's the problem this PR addresses?

The GitHub CLI requires setting the GH_TOKEN environment variable in order to use it.

Fixes https://github.com/yarnpkg/berry/actions/runs/5427185945/jobs/9870161176#step:6:414

gh: To use GitHub CLI in a GitHub Actions workflow, set the GH_TOKEN environment variable. Example:
  env:
    GH_TOKEN: ${{ github.token }}

How did you fix it?

Set the environment variable.

Verified this works with 87a0d81 to create https://github.com/yarnpkg/berry/releases/tag/%40yarnpkg%2Fcli%2F3.6.1.

Checklist

• I have read the Contributing Guide.
• I have set the packages that need to be released for my changes to be effective.
• I will check that all automated PR checks pass before the PR gets reviewed.