BUG/MINOR: spoa/python: Cleanup references for failed Module Addobject operations

BUG/MINOR: spoa/python: Cleanup references for failed Module Addobject operations

As per https://docs.python.org/3/c-api/module.html#c.PyModule_AddObject,
references are stolen by the function only for success. We must do
cleanup manually if there is a failure

This patch must be backported as far as 2.0.

(cherry picked from commit 132d8f61e9440b9254069ca2c4bcff67df29bb6f)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 2efe413b82d4fd35178ecb96e7b5f4336deb4cc5)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit e795c1f99bb9c99369aac2a97e2447a215176089)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>