bump default NodeJS version to 20 LTS (#2061)

.github/workflows/style.yml

       - name: Setup NodeJS
         uses: actions/setup-node@v4
         with:
-          node-version: 18
+          node-version: 20
           cache: yarn
           cache-dependency-path: ./web/package.json
 

web/Dockerfile

 # base image
-FROM node:18.17.0-alpine AS base
+FROM node:20.11.0-alpine AS base
 
 # install packages
 FROM base as packages
 ENV COMMIT_SHA ${COMMIT_SHA}
 
 EXPOSE 3000
-ENTRYPOINT ["/bin/sh", "./entrypoint.sh"]
+ENTRYPOINT ["/bin/sh", "./entrypoint.sh"]