Avoid confluent-kafka 2.1.0

requirements.txt

 # Add here external Python modules dependencies, one per line. Module names
 # should match https://pypi.python.org/pypi names. For the full spec or
 # dependency lines, see https://pip.readthedocs.org/en/1.1/requirements.html
-confluent-kafka
+
+# 2.1.0 is prone to segfaults, see upstream issue gh:confluentinc/confluent-kafka-python#1547
+confluent-kafka != 2.1.0
+
 msgpack >= 1.0.0, != 1.0.1
 tenacity