rdkafka 6.0.0RC1

Kafka client based on librdkafka

PHP-rdkafka is a stable Kafka client for PHP based on librdkafka

License: MIT License

Changes

## Enhancements
- PHP 8.1 support (@ruudk, @remicollet, @nick-zh, @arnaud-lb)

## Breaking changes
- Added tentative return types in PHP 8.1 builds