Escape the sed command for removing a line in fed/centos lighttpd.conf

Signed-off-by: Adam Warner <me@adamwarner.co.uk>

automated install/basic-install.sh

@@ -1010,7 +1010,7 @@ remove_old_pihole_lighttpd_configs() {
 
     if [[ -d "/etc/lighttpd/conf.d" ]]; then
         if grep -q -F 'include "/etc/lighttpd/conf.d/pihole-admin.conf"' "${lighttpdConfig}"; then
-           sed -i '/include "/etc/lighttpd/conf.d/pihole-admin.conf"/d' "${lighttpdConfig}"
+           sed -i '/include "\/etc\/lighttpd\/conf.d\/pihole-admin.conf"/d' "${lighttpdConfig}"
         fi
 
         if [[ -f "${condfd}" ]]; then