Bundled Themes: Twenty Twenty custom post types that don't support authors, shows author box.

This fixes the issue where custom post types will show an author box, even if they don't support authors.

Props joyously, donmhico.
Fixes #48803.
Built from https://develop.svn.wordpress.org/trunk@47799


git-svn-id: https://core.svn.wordpress.org/trunk@47575 1a063a9b-81f0-0310-95a4-ce76da25c4cd