* update Composer dependencies (PHP 8.1+, PHPUnit 10, Psalm 5)
* make PHPUnit data provider methods static
* remove obsolete doc blocks
* use constructor property promotion
* deprecate getter methods
* mark constants as final
* use arrow functions
* code style
* throw JsonException when encoding fails
* use typed properties
* update return types
* use public properties instead of deprecated getters
* update Psalm config
* update README + change log
* update docs
* update GitHub Actions version matrix
* update change log