Handle GitHub rate-limits in ACUL commands by falling back to stable version

[ramya18101]

🔧 Changes

• Updated ACUL version resolution to treat GitHub release tag discovery as best-effort instead of a hard dependency.
• auth0 acul init now falls back to a known stable ACUL version when the latest tag cannot be fetched due to GitHub rate limiting or network issues.
• auth0 acul screen add continues to use the ACUL version stored in acul_config and no longer fails when tag discovery is unavailable.
• Version compatibility checks are now informational only and never block command execution.

📚 References

• Customer reports of 403 errors when accessing GitHub /tags endpoint

🔬 Testing

• Verified auth0 acul init continues successfully when GitHub /tags returns 403.
• Verified auth0 acul screen add continues using the version from acul_config.
• Verified warning messages are non-blocking and do not interrupt command execution.

📝 Checklist

• All new/changed/fixed functionality is covered by tests (or N/A)
• I have added documentation for all new/changed functionality (or N/A)