use Node.js 16 instead of Node.js 14 in Dockerfile

The previously used Node.js 14 is an old LTS version that has
reached its end of support in April 2023, so it should no longer
be used.

I would even go further and update to Node.js 18 or Node.js 20,
but the Dockerfile job on GitHub Actions fails for a yet unknown
reason when the container has to start with Node.js 18 or 20:

    curl: (7) Failed to connect to 127.0.0.1 port 3000 after 0 ms: Connection refused

Needs more investigating, but for now a smaller update that works
(Node.js 16) is still better than no update at all.

Dockerfile

@@ -19,9 +19,9 @@ RUN apt-get update && apt-get upgrade -y && \
  ca-certificates \
  libfontconfig1
 # Node.js is required to run this application.
-RUN echo "# Node.js 14.x for Debian 11 (codename bullseye)" > /etc/apt/sources.list.d/nodejs.list \
- && echo "deb https://deb.nodesource.com/node_14.x bullseye main" >> /etc/apt/sources.list.d/nodejs.list \
- && echo "deb-src https://deb.nodesource.com/node_14.x bullseye main" >> /etc/apt/sources.list.d/nodejs.list
+RUN echo "# Node.js 16.x for Debian 11 (codename bullseye)" > /etc/apt/sources.list.d/nodejs.list \
+ && echo "deb https://deb.nodesource.com/node_16.x bullseye main" >> /etc/apt/sources.list.d/nodejs.list \
+ && echo "deb-src https://deb.nodesource.com/node_16.x bullseye main" >> /etc/apt/sources.list.d/nodejs.list
 RUN apt-key adv --fetch-keys https://deb.nodesource.com/gpgkey/nodesource.gpg.key
 RUN apt-get update && apt-get install --no-install-recommends -y nodejs
 # Create directory for application.

changelog.md

@@ -10,6 +10,11 @@ Since [ECharts](https://echarts.apache.org/) is the main dependency of this
 application, major version changes in ECharts will also trigger a major version
 change in this application.
 
+## Version 5.?.? (2024-05-??)
+
+* __[maintenance]__
+Update Dockerfile to use Node.js 16 instead of Node.js 14.
+
 ## Version 5.1.2 (2024-03-31)
 
 * __[maintenance]__