I’m not sure why push rules are listed in the GitLab CE (9.0.0) changelog. It would seem that they are a feature only available in the Starter/Bronze plans for GitLab EE:
Hi, please don’t double-post. Your question was answered in the other one: Gitlab Push Rules feature in CE - #2 by iwalker - it is a premium feature, so no, it does not exist in CE or EE without premium subscription.