Added pkgs number for distros that use apt

[SimoneSalzano]

By storing OS name in a variable, we can use it to get the number of packages from the package manager corresponding to the chosen OS:

os=$(awk -F '"' '/PRETTY/ {print $2}' /etc/os-release)
pkgs=""
case $os in 
*"Ubuntu"*|*"Mint"*|*"Debian"*|*"Pop!_OS")
    pkgs=$(dpkg-query -l | grep "^ii" | wc -l)
    ;;
*"Arch"*)
    pkgs=$(pacman -Q | wc -l)
    ;;
esac

We can easily do this for other package managers by adding more cases.