use php version 7.3 instead of 8 ubuntu code example

Example 1: install php 7.3 ubuntu

sudo apt install php7.3-cli php7.3-fpm php7.3-json php7.3-pdo php7.3-mysql php7.3-zip php7.3-gd  php7.3-mbstring php7.3-curl php7.3-xml php7.3-bcmath php7.3-json

Example 2: install php 8 ubuntu

sudo apt update
sudo apt install lsb-release ca-certificates apt-transport-https software-properties-common -y
sudo add-apt-repository ppa:ondrej/php