Fix/aiokafka 0.13 compatibility (#4379)

* tests(aiokafka): bump aiokafka 0.13

* tests(aiokafka): remove removed api_version argument from AIOKafkaProducer

* fix(aiokafka): call serializers directly instead of _serialize

* chore: add CHANGELOG entry for aiokafka 0.13 compatibility fix

* tests(aiokafka): align tests to support python 3.9

* Apply suggestion from @xrmx

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Co-authored-by: Emídio Neto <9735060+emdneto@users.noreply.github.com>
Co-authored-by: Riccardo Magliocchetti <riccardo.magliocchetti@gmail.com>