Why has coverage been locked to `==4.0.3` for two years? Why not `>=4.0.0`?

If I add localstack to my pipenv, I can't lock because of this unnecessary dependency.
testutil.create_lambda_function(func_name=TEST_CHAIN_LAMBDA1_NAME, zip_file=zip_file,
        event_source_arn=get_event_source_arn(TEST_CHAIN_STREAM1_NAME), runtime=LAMBDA_RUNTIME_PYTHON27)
    testutil.create_lambda_function(func_name=TEST_CHAIN_LAMBDA2_NAME, zip_file=zip_file,
        event_source_arn=get_event_source_arn(TEST_CHAIN_STREAM2_NAME), runtime=LAMBDA_RUNTIME_PYTHON27)
    # pu
    test_data = {'test_data': 'forward_chain_data_%s' % short_uid()}
    data = clone(test_data)
    data[lambda_integration.MSG_BODY_MESSAGE_TARGET] = 'kinesis:%s' % TEST_CHAIN_STREAM2_NAME
    kinesis.put_record(Data=to_bytes(json.dumps(data)), PartitionKey='testId', StreamName=TEST_CHAIN_STREAM1_NAME)
    # ch
    time.sleep(5)
    all_objects = testutil.list_all_s3_objects()
    testutil.assert_objects(test_data, all_objects)
# ---------------
# HELPER METHODS
# ---------------
def get_event_source_arn(stream_name):
    kinesis = aws_stack.connect_to_service('kinesis')
    return kinesis.describe_stream(StreamName=stream_name)['StreamDescription']['StreamARN']
def get_lambda_metrics(func_name, metric='Invocations'):
    return cloudwatch_util.get_metric_statistics(
        Namespace='AWS/Lambda',
        MetricName=metric,
        Dimensions=[{'Name': 'FunctionName', 'Value': func_name}],
        Period=60,
        StartTime=datetime.now() - timedelta(minutes=1),
        EndTime=datetime.now(),
        Statistics=['Sum']
    )