Use node-18 in dockerfile

Dockerfile

-FROM node:16-slim as build-env
+FROM node:18-slim as build-env
 LABEL maintainer="ui-team@open-xchange.com"
 
 WORKDIR /app
 ADD . /app
 RUN yarn --production --non-interactive --no-progress -s
 
-FROM gcr.io/distroless/nodejs:16
+FROM gcr.io/distroless/nodejs:18
 USER 1000
 
 ARG APP_VERSION