feat: add GitHub token authentication support

[azrsh]

Summary

Adds optional GitHub token authentication support to the aqua-installer script, enabling authenticated downloads when the GITHUB_TOKEN environment variable is available. The action.yaml sets the GITHUB_TOKEN environment variable, so the aqua-installer action user can utilize their token to fetch the aqua binary.
This moves the request from IP-address-based GitHub rate limit budget to identity-based one, which has higher rate limits.

https://docs.github.com/en/rest/using-the-rest-api/rate-limits-for-the-rest-api?apiVersion=2022-11-28

Changes Made

• Rate Limit Benefits: Authenticated requests get higher GitHub API rate limits (1,000/hr vs 60/hr on the primary rate limit)
• Conditional Authentication: Uses Authorization: Bearer header when GITHUB_TOKEN is set
• Backward Compatibility: Maintains existing unauthenticated behavior when no token is provided

Benefits

• Higher Rate Limits: Authenticated requests avoid GitHub's strict rate limiting
• Future-Proof: Aligns with GitHub's recommended authentication practices
• Zero Breaking Changes: Existing usage patterns continue to work unchanged

Usage

# Existing usage (unchanged)
./aqua-installer

# New authenticated usage
GITHUB_TOKEN=ghp_xxxxxxxxxxxx ./aqua-installer

Testing

• Tested with both curl and wget
• Verified backward compatibility with unauthenticated requests
• Confirmed proper header formatting for GitHub API authentication

[suzuki-shunsuke]

aqua-installer/aqua-installer

Line 66 in c780ffb

URL=https://github.com/aquaproj/aqua/releases/download/$bootstrap_version/$filename

The endpoint isn't GitHub REST API.
IIRC, there is no rate limit for this endpoint the API rate limit for GitHub REST API isn't applied to this endpoint.

[suzuki-shunsuke]

If you have any trouble, could you create an issue first?

[azrsh]

@suzuki-shunsuke Thank you for your response! We are facing some 403 errors (which is usually the rate limit errors on GitHub), but if the endpoint doesn't have the rate limit, then the cause can be another factor. Let me try to investigate a bit more 🙇