Update zigbee2mqtt.sh

(node 18.x has stopped utilizing npm by default)

- check if the installed version of Node.js is 18.x and, if so, ensures that npm is also installed.
- fixes https://github.com/tteck/Proxmox/issues/2281

ct/zigbee2mqtt.sh

@@ -57,6 +57,13 @@ function update_script() {
     msg_error "No ${APP} Installation Found!"
     exit
   fi
+  if [[ "$(node -v | cut -d 'v' -f 2)" == "18."* ]]; then
+    if ! command -v npm >/dev/null 2>&1; then
+      echo "Installing NPM..."
+      apt-get install -y npm >/dev/null 2>&1
+      echo "Installed NPM..."
+    fi
+  fi
   cd /opt/zigbee2mqtt
 
   stop_zigbee2mqtt() {