Log Message:
www/drupal8: update to 8.9.20

This is last release of Drupal 8.x.

8.9.20 (2021-11-17)

This release fixes security vulnerabilities. Sites are urged to update
immediately after reading the notes below and the security announcement:

Drupal core - Critical - Third-party library - SA-CORE-2021-011

No other fixes are included.