Merge pull request wintoncode#52 from ah-/asynchronous

Use commit asynchronous for python 3.7 compatibility

Author: ah-

setup.py

@@ -13,7 +13,7 @@
 
 requirements = [
     'javaproperties',
-    'confluent-kafka',
+    'confluent-kafka>=0.11.4',
     'requests',
     'avro-python3'
 ]

winton_kafka_streams/processor/_stream_task.py

@@ -162,7 +162,7 @@ def commit_offsets(self):
         try:
             if self.commitOffsetNeeded:
                 offsets_to_commit = [TopicPartition(t, p, o + 1) for ((t, p), o) in self.consumedOffsets.items()]
-                self.consumer.commit(offsets=offsets_to_commit, async=False)
+                self.consumer.commit(offsets=offsets_to_commit, asynchronous=False)
                 self.consumedOffsets.clear()
                 self.commitOffsetNeeded = False