the make file of kafka_test needs to revert too (#2074)

Author: Tian-2017

lambdas/kafka_test/Makefile

@@ -7,6 +7,6 @@ install-requirements:
 
 	. venv/bin/activate && sudo pipenv lock --requirements > requirements.txt
 	#. venv/bin/activate && sudo pip install --target ./lib -r requirements.txt
-	. venv/bin/activate && sudo docker run -v $(PWD):/var/task "lambci/lambda:build-python3.9" /bin/sh -c "pip install --target ./lib -r requirements.txt; exit"
+	. venv/bin/activate && sudo docker run -v $(PWD):/var/task "lambci/lambda:build-python3.8" /bin/sh -c "pip install --target ./lib -r requirements.txt; exit"
 	sudo cp ../../terraform/modules/kafka-schema-registry/schemas/* ./lib/
 	rm -rf venv/