Prepare 4.0.0

[julien-nc]

Added

• Add simple integration test making requests to Nominatim @julien-nc #50

Changed

• Start refactoring the map component, allow v-model on map state props, update the directions plugin for breaking changes, and refresh npm/composer tooling @julien-nc #27
• Switch to outlined icons @julien-nc #29
• Modernize settings @julien-nc #28
• Switch from psalm/phar to vimeo/psalm and update composer dependencies @julien-nc #49
• Bump supported Nextcloud version to 34, replace IConfig with IUserConfig, move to PHPUnit 13, align PHP versions in tooling, and display PHPUnit deprecations, warnings, and notices @julien-nc #59
• Update npm and composer dependencies @julien-nc

Fixed

• Fix getting headers of HTTP responses in the backend @julien-nc