PHP7.2XXX 에서 PHP7.3XXX 으로 안전하게 업그레이드 하기

php7.3 will be updated automatically when updates become available. Alternatively you can build php7.3 from source in Ubuntu 18.04, but it will not be updated automatically, and it also takes more than an hour to build if you want to test it too.

참조 : https://forum.yiiframework.com/t/yii-1-1-21-and-php-7-2-19-issues/126343