Update php (#20610)

Changes:

- docker-library/php@6485b53a: Set `sysconfdir` explicitly during build (docker-library/php#1636)
- docker-library/php@f26909cd: Move fpm listen for easier config override (docker-library/php#1635)
- docker-library/php@bc5b3fdc: Move `variants` calculation into `jq` (docker-library/php#1640)
- docker-library/php@91d35430: Post 8.1 EOL cleanup (docker-library/php#1642)

Co-authored-by: Docker Library Bot <doi+docker-library-bot@docker.com>

Author: yosifkit