rdkafka 5.0.0

Kafka client based on librdkafka

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

License: MIT License

Changes

## Enhancements
- PHP 8 support (@nick-zh, @arnaud-lb)
- Suport passing an opaque value in produce(), producev() (@arnaud-lb)

## Breaking changes
- Dropped PHP 5 support