Changelog since v0.18.3

⬆️ Upgrades add-on base image to 13.1.1 (#332)
🎆 Updates maintenance/license year to 2023 (#331)
🔨 Migrate old-style S6 scripts to s6-rc.d (#327)
⬆️ Upgrades add-on base image to 13.0.0 (#324)