php: security bump to version 7.2.13

php: security bump to version 7.2.13

Fixes CVE-2018-19518: University of Washington IMAP Toolkit 2007f on UNIX,
as used in imap_open() in PHP and other products, launches an rsh command
(by means of the imap_rimap function in c-client/imap4r1.c and the tcp_aopen
function in osdep/unix/tcp_unix.c) without preventing argument injection,
which might allow remote attackers to execute arbitrary OS commands if the
IMAP server name is untrusted input (e.g., entered by a user of a web
application) and if rsh has been replaced by a program with different
argument semantics.  For example, if rsh is a link to ssh (as seen on Debian
and Ubuntu systems), then the attack can use an IMAP server name containing
a "-oProxyCommand" argument.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>