Authenticate GitHub requests

[rgoldberg]

Three GitHub Action Workflows failed yesterday, like:

https://github.com/mas-cli/mas/actions/runs/11534974563

With the error:

GitHub API Error: API rate limit exceeded for <REDACTED IP ADDRESS>. (But here's the good news: Authenticated requests get a higher rate limit. Check out the documentation for more details.)
Try again in 60 minutes, or:
Create a GitHub personal access token:
  https://github.com/settings/tokens/new?scopes=gist,repo,workflow&description=Homebrew
echo 'export HOMEBREW_GITHUB_API_TOKEN=your_token_here' >> /Users/runner/.bash_profile

We should therefore authenticate GitHub requests.

The first 3 bytes of each of the IP addresses were the same for all the failures, but the last byte was different for each.

I don't know what account we're supposed to authenticate for:

• the mas-cli organization
• the account that performed the event that triggered the workflow, etc.

I don't know GitHub Actions or Workflows, so I assigned @phatblat, as he's working on the release process. If you, @phatblat, don't have the time to work on it, it can be shelved for later, or I can learn all about GitHub Actions & Workflows, then investigate, but it should take me some time starting from scratch.