ORG: v0.5.1 - Bump patch version to 0.5.1

[munterfi]

Draft new release v0.5.1 to conclude the current sprint.

Release notes:

## public-transit-service 0.5.1

This release introduces performance enhancements of the raptor router and a transition to the MIT license.

### New Features
- **Performance Optimization in Raptor Rounds**: Improved performance by replacing the HashSet for marked stops with boolean stop mask arrays.
- **Sorted Stop Results**: Stops are now sorted by name in the `getStops(String like)` API to enhance the user experience.
- **MIT License**: Changed project licensing from GPLv3 to MIT for better alignment with open-source best practices.

### Bug Fixes
- **Range Raptor Fix**: Resolved an issue where Range RAPTOR failed to return routes when no departure was found, ensuring reliable route results.

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[clukas1]

Changes look good, removed an unused function while reviewing.