BUG/MINOR: contrib/spoa-server: Ensure ip address references are freed

BUG/MINOR: contrib/spoa-server: Ensure ip address references are freed

IP addresses references passed in argument for ps_python are not freed after
they have been used. Leading to a small chance of mem leak if a lot of ip
addresses are passed around

This patch must be backported as far as 2.0.

(cherry picked from commit 9f0c984cf50fee3a2282993b573be2f049efe5ab)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit a77f10426189fe48bca2c3543e65510933b95272)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>