Add PHP 8.0 to Pantheon's entry. Also update patch version for 7.3 and 7.4, and update default version to 7.4.
Add PHP 8.0 to Pantheon's entry. Also update patch version for 7.3 and 7.4, and update default version to 7.4.

po2go-sean/phpversions.info,po2go-sean/phpversions.info,phpversions/phpversions.info,po2go-sean/phpversions.info,phpversions/phpversions.info,phpversions/phpversions.info,phpversions/phpversions.info,po2go-sean/phpversions.info