package/expat: security bump to version 2.4.1

Fix CVE-2013-0340 "Billion Laughs":
https://blog.hartwork.org/posts/cve-2013-0340-billion-laughs-fixed-in-expat-2-4-0/

https://github.com/libexpat/libexpat/blob/R_2_4_1/expat/Changes



Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>