update bootstrap role for arch

roles/bootstrap/tasks/main.yml

@@ -4,6 +4,7 @@
        bash -c "test -e /usr/bin/python3 || 
        (test -e /usr/bin/yum && yum install -y python3) || 
        (apt install -y python3 python-apt) || 
+       (pacman -S python --noconfirm) ||
        grep -i LibreELEC /etc/os-release"
   changed_when: false