Update copyright year to 2020 in bundled themes' `readme.txt`. Built from https://develop.svn.wordpress.org/trunk@47026 git-svn-id: http://core.svn.wordpress.org/trunk@46826 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Add a unit test to ensure the year stays up to date. Props dkarfa, SergeyBiryukov. Fixes #48566. Built from https://develop.svn.wordpress.org/trunk@46719 git-svn-id: http://core.svn.wordpress.org/trunk@46519 1a063a9b-81f0-0310-95a4-ce76da25c4cd