This upgrades Kafka from 2.6 to 3.2 and Zookeeper from 3.4 to 3.7.
From your commcare-hq directory, run the following:
git checkout gh/upgrade-kafka-container
./scripts/docker up -d kafka zookeeper
You should now be running the updated containers.
If for some reason your kafka container fails to start, try ./scripts/docker rm -sv kafka zookeeper
followed by step 2 again.