package/php: security bump version to 7.3.9

Release notes: https://www.php.net/archive/2019.php#2019-08-29-1
Changelog: https://www.php.net/ChangeLog-7.php#7.3.9

Fixes CVE-2019-13224 & CVE-2019-13225:
https://bugs.mageia.org/show_bug.cgi?id=25380



Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>