update php version in ubuntu 16.04 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 16 upgrade php 7.0 to 7.4

sudo apt install -y php7.4 php7.4-cli php7.4-common php7.4-fpm