[all][oslo] Generation of sample policy files broken since oslo.policy 3.12.0

Hello, While updating sample policy files (those with all rules commented out and including comments) in CloudKitty, I discovered that the functionality was broken: oslo.policy generates an actual policy file instead [1]. This issue was first introduced in 3.12.0. I submitted a fix [2] which I assume will ship in the next release. I thought this was worth sharing since any project using output from oslopolicy-sample-generator in their docs or repository could be impacted. A workaround is to stick to oslo.policy 3.11.0 in your genpolicy tox environment. Cheers, Pierre Riteau (priteau) [1] https://bugs.launchpad.net/oslo.policy/+bug/1975682 [2] https://review.opendev.org/c/openstack/oslo.policy/+/843250