Upgrade Weblate to latest 5.x

Ref: #17890 (closed)

• Adapt integration scripts tests for latest Weblate -- puppet-weblate!8 (merged)
• Check feasibility of upgrading to latest 5.x
• Check if a patched settings_docker.py is still needed
• Manually test to check whether integration scripts work as expected.
• Schedule the upgrade and inform tails-l10n
• Upgrade Weblate to latest 5.x
  • Protect the instance with a password to prevent modifications
  • Make sure there are no pending commits
  • Make sure cron.sh is working fine
  • Save a copy of the repositories and database
  • Upgrade to 5.0.2
  • Upgrade to 5.2
  • Check that Weblate works fine
  • Check that cron.sh works fine
  • Remove password from production instance
• Upgrade Weblate to version 5.3.0.1 -- puppet-weblate!9 (merged)
• Review / document the upgrade process
• Feedback on tails#18308 (closed)