- added AppConfig.default_auto_field to lock ID-fields in order to avoid migrations if projects use a different field in their settings
- added missing migration due to updated holidays version
- fixed holidays on version 0.18 -> newer versions may result in new migrations which may be problematic if this app is integrated as a third-party-app
- updated the testing environment
- dropped django<3.0 support
- added support for django 4.0 and 4.1
- enabled newer versions for holidays dependency