Release/v0.4.0

[munterfi]

Draft new release v0.4.0 to conclude the current sprint.

Release notes:

## public-transit-service 0.4.0

This release focuses on enhancing the router's capabilities (multiday and range Raptor), refactoring, and improving the overall user experience with the service.

### New Features
- **Multiday Routing Support**: The Raptor now supports queries for connections that span multiple days, based on a new `TripMaskProvider` concept.
- **Range Raptor**: The public transit service is now capable of applying Range Raptor searches to obtain the shortest connections.
- **Improved Error Handling in REST API**: Enhanced the application's error-handling mechanism, particularly by checking for valid parameters and existing stops.
- **Service Home and Utility Endpoints**: A new homepage is available under the service root (`/`) with information about the version and useful links to metrics, health, and build information.
- **OpenAPI Support**: A Swagger UI and API documentation are now automatically generated and served under the service home.
- **GTFS Accessibility Information**: Accessibility and bike information are now read into the GTFS schedule, if available.

### Bug Fixes
- **Docker Deployment**: Fixed incorrect environment variable names.
- **GTFS Calendar**: The conditionally required files `calendars.txt` and `calendar_dates.txt` are now read correctly in all valid combinations.

--> PLACE AUTOMATICALLY GENERATED CHANGELOG HERE

[clukas1]

Looks good