Update node to 16.16 & run npm update

Due to an update in the default repositories in the underlying `alpine` image, `python` no longer refers to the correct version for our build. Changing it to `python3` will allow the build to complete succesfully.

Ideally we'd update to version 18 straight away, but that seems a bit less straightforward. Updating to version 16 (which has security support until september 11th 2023) buys us time to come up with a good strategy to upgrade further.

Dockerfile

@@ -1,5 +1,5 @@
 # Nodejs 8.0.0 alpine 3.6.0
-FROM node:13.14.0-alpine
+FROM node:16.16.0-alpine
 
 # Label for tracking
 LABEL nl.openstad.container="frontend" nl.openstad.version="0.0.1-beta" nl.openstad.release-date="2020-05-07"
@@ -35,7 +35,7 @@ ENV S3_BUCKET=""
 
 
 # Install all base dependencies.
-RUN apk add --no-cache --update openssl g++ make python musl-dev git bash
+RUN apk add --no-cache --update openssl g++ make python3 musl-dev git bash
 
 
 # Set the working directory to the root of the container
@@ -54,7 +54,7 @@ RUN npm install --loglevel warn --production
 RUN npm install -g nodemon
 
 # Remove unused packages only used for building.
-RUN apk del openssl g++ make python && rm -rf /var/cache/apk/*
+RUN apk del openssl g++ make python3 && rm -rf /var/cache/apk/*
 
 RUN mkdir -p /home/app/public
 RUN mkdir -p /home/app/public