Upgrade to Node 20

Use the new nodesource-recommended means of installing node, which
fixes the problems of npm not being found at build time

Dockerfile

@@ -5,11 +5,18 @@ ENV PYTHONUNBUFFERED 1
 RUN pip install pipenv
 RUN pip install --upgrade pip setuptools wheel
 
+RUN apt-get update
+RUN apt -y dist-upgrade
+RUN apt-get install -y ca-certificates curl gnupg
+RUN mkdir -p /etc/apt/keyrings
+RUN curl -fsSL https://deb.nodesource.com/gpgkey/nodesource-repo.gpg.key | gpg --dearmor -o /etc/apt/keyrings/nodesource.gpg
+
 # Adds our application code to the image
 COPY . /code
 WORKDIR /code
 
-RUN bash /code/setup_node_16.sh
+ENV NODE_MAJOR 20
+RUN echo "deb [signed-by=/etc/apt/keyrings/nodesource.gpg] https://deb.nodesource.com/node_$NODE_MAJOR.x nodistro main" | tee /etc/apt/sources.list.d/nodesource.list
 RUN apt-get update && apt-get -y dist-upgrade && apt-get -y install libmemcached-dev nodejs
 
 # the version of node-sass that tailwind uses doesn't work with npm 5.x under node 10.x, which the debian docker image gives us