Dockerfile: update node.js to 20

Updates node.js to the current active LTS version. Version 16
seems unmaintained at this time. See
https://nodejs.org/en/about/previous-releases

Author: schildbach

Dockerfile

@@ -1,9 +1,9 @@
-FROM node:16 as builder
+FROM node:20 as builder
 WORKDIR /workspace
 COPY . .
 RUN npm install
 
-FROM node:16-alpine
+FROM node:20-alpine
 WORKDIR /workspace
 COPY --from=builder /workspace .
 RUN apk --update add git