Apple has today pushed an update to the configuration data used by Gatekeeper, bringing it to version 135.

No information about the update is provided, but it is usually assumed to revoke code signing and other certificates which have been abused or withdrawn.

You can check whether this update has been installed by opening System Information via About This Mac, and selecting the Installations item under Software.

A full listing of security data file versions is given by LockRattler and SystHist for El Capitan, Sierra and High Sierra, available from Downloads above.

I maintain lists of the current versions of security data files for Sierra on this page, for High Sierra on this page, and for El Capitan on this page.