Future Release Branches Frozen For Merging | branch:release-4.20 branch:release-4.21

The following branches are being fast-forwarded from the current development branch (main) as placeholders for future releases. No merging is allowed into these release branches until they are unfrozen for production release. - `release-4.20` - `release-4.21` For more information, see the [branching documentation](https://docs.ci.openshift.org/docs/architecture/branching/).