Replace bespoke NullHandler with Python's impl

Author: nateprewitt

s3transfer/__init__.py

@@ -134,6 +134,7 @@ def __call__(self, bytes_amount):
 import socket
 import string
 import threading
+from logging import NullHandler
 
 from botocore.compat import six  # noqa: F401
 from botocore.exceptions import IncompleteReadError, ResponseStreamingError
@@ -148,11 +149,6 @@ def __call__(self, bytes_amount):
 __version__ = '0.13.0'
 
 
-class NullHandler(logging.Handler):
-    def emit(self, record):
-        pass
-
-
 logger = logging.getLogger(__name__)
 logger.addHandler(NullHandler())