Automatic deploy from gitlab/salsa CI

At SnowCamp I migrated Front Desk-related repositories to Salsa gitlab and worked on setting up Continuous Integration for the web applications I maintain in Debian.

The result is a reusable Django app that integrates with gitlab's webhooks

It is currently working for https://contributors.debian.org and I'll soon reuse it for https://nm.debian.org and https://debtags.debian.org.

The only setup needed on DSA side is to enable systemd linger on the deploy user.

The CI/deploy workflow is this:

And manage.py deploy does this:

For more details, see the app's README.md

I find it wonderful that we got to a stage where we can have this in Debian, and I am very grateful to all the work that has been done and is being done in setting up and maintaining Salsa.