Remove trailing comma

I don't know how this happened, I think black added it? But then it didn't re-add it this time when I removed it. Probably more of black's magic comma stuff that has been added recently

Author: basepi

elasticapm/transport/base.py

@@ -70,7 +70,7 @@ def __init__(
  queue_chill_count=500,
  queue_chill_time=1.0,
  processors=None,
- **kwargs,
+ **kwargs
  ):
  """
  Create a new Transport instance