Issue #3281454 by _shY, pooja saraah, deviantintegral, quietone, alexpott, nod_: Update various module tests to not use Bartik and Seven

Issue #3072702 by alexpott, Wim Leers, mikelutz, xjm, catch, Berdir, tedbow, webchick, shaal, Mixologic, heddn: Core extensions should not need to specify the new core_version_requirement in *.info.yml files so that 9.0.x can be installed

Issue #2228125 by dawehner: 'base theme' property in theme .info.yml files does not need to be wrapped in quotes

Issue #2271529 by attiks, alexpott, Lowell, YesCT, Jelle_S | mdrummond: Move breakpoint settings to theme and module *.breakpoints.yml files at root level.

Issue #2095943 by dotoree, Tim Bozeman: Core modules and themes missing the version attribute in info.yml.