Reinit keyring

killall gpg-agent
rm -rf /etc/pacman.d/gnupg
pacman-key --init
pacman-key --populate archlinux
pacman -Sy archlinux-keyring

Install Paru

sudo pacman -S --needed base-devel
git clone https://aur.archlinux.org/paru.git
cd paru
makepkg -si