upgrade to php 7.3 code example
Example 1: update php version ubuntu 7.3
sudo apt-get install software-properties-common
sudo add-apt-repository ppa:ondrej/php
sudo apt-get update
sudo apt-get upgrade
sudo apt-get install -y php7.3
Example 2: ubuntu upgrade php to 7.3
sudo apt-get install software-properties-common
sudo add-apt-repository ppa:ondrej/php
sudo apt-get update
sudo apt-get upgrade
sudo apt-get install -y php7.3