Release v4.12.4

What's Changed

• wording: update frontpage by @utnapischtim in #306
• workflows: change to reusable workflows by @utnapischtim in #307
• fix: types could be empty list by @utnapischtim in #309
• ui: add 423 error page by @utnapischtim in #310
• release v4.12.4 by @utnapischtim in #311

Full Changelog: v4.12.3...v4.12.4