package/php: security bump version to 7.4.12

Changelog: https://www.php.net/ChangeLog-7.php#7.4.12

According to the release notes this is a "security bug fix release":
https://news-web.php.net/php.announce/300



Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>