fix: add CERT variable to standalone frontend startup

Author: ludomikula

deploy/docker/frontend/01-update-nginx-conf.sh

@@ -2,6 +2,8 @@
 
 set -e
 
+CERT="/lowcoder-stacks/ssl"
+
 echo "Creating nginx config..."
 if [ -e "${CERT}/fullchain.pem" ] && [ -e "${CERT}/privkey.pem" ]; then
    echo "Certificates found, configuring with HTTPS."