[Trivial] Remove executable privilege of doc/source/conf.py
[Trivial] Remove executable privilege of doc/source/conf.py

It is a configuration file, rather than a script.

Change-Id: Ifa29b9d117ff082b063e117e54707f35a239fc50

openstack/magnum,jay-lau/magnum,openstack/magnum,ArchiFleKs/magnum,ArchiFleKs/magnum