[NOJIRA] Bump datadog-sbom-generator to v1.13.1

[rjcoulter22]

🚀 Motivation

Update the GitHub Action to stay in sync with the latest stable datadog-sbom-generator release so users pick up upstream parser additions and bug fixes (e.g. lockfile-less JS package.json extractor, MANIFEST.MF fallback parser for JARs, Bun lockfile parser).

📝 Summary

• Bumps SBOMGEN_VERSION in action.yml from 1.11.3 to 1.13.1 - see release details

🧪 Testing

• Tested on ubuntu, macos, and windows CI runners to verify action worked successfully

🆘 Recovery

Notes for on-call - select only one:

• The change can be rolled back.
• Do not roll back. Why?: