Pass repo-token to binary downloads to avoid rate limiting

[Copilot]

The action was hitting GitHub's rate limit (60/hr unauthenticated) when downloading protoc binaries. The repo-token parameter was only being used for release API calls, not for the actual binary downloads via tc.downloadTool().

Changes

• downloadRelease(): Now accepts and uses repoToken parameter
• getProtoc(): Passes repoToken through to downloadRelease()
• tc.downloadTool(): Now called with authentication header

// Before
downloadPath = await tc.downloadTool(downloadUrl);

// After
const auth = repoToken ? `token ${repoToken}` : undefined;
downloadPath = await tc.downloadTool(downloadUrl, undefined, auth);

When repo-token: ${{ secrets.GITHUB_TOKEN }} is provided, downloads are authenticated (5000/hr limit vs 60/hr).

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• https://api.github.com/repos/protocolbuffers/protobuf/releases
  • Triggering command: /usr/local/bin/node node /home/REDACTED/work/setup-protoc/setup-protoc/node_modules/.bin/jest (http block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

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✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[thangktran]

LGTM