Description
Can't pickle KafkaException, wrong import. When i use celery, and celery use pickle to serialization, i get this error:
''PicklingError("Can't pickle <class 'cimpl.KafkaException'>: import of module 'cimpl' failed")''

How to reproduce

import pickle
import confluent_kafka
e = confluent_kafka.KafkaException()
pickle.dumps(e)

Result:
_pickle.PicklingError: Can't pickle <class 'cimpl.KafkaException'>: import of module 'cimpl' failed

Also i tried with confluent_kafka.cimpl.KafkaException() and confluent_kafka.error.KafkaException(), and got the same result.

Checklist

• confluent-kafka-python and librdkafka version ('2.3.0', 33751040):
• Operating system: ios