www/node21: Update to 21.6.2
Changes: https://github.com/nodejs/node/releases
https://github.com/nodejs/node/blob/main/doc/changelogs/CHANGELOG_V21.md
Security: CVE-2023-46809, CVE-2024-21890, CVE-2024-21891, CVE-2024-21892, CVE-2024-21896, CVE-2024-22017, CVE-2024-22019, CVE-2024-22025