Fix constructor args of logging Formatter

Author: leplatrem

src/dockerflow/logging.py

@@ -77,9 +77,9 @@ def __init__(self, fmt=None, datefmt=None, style="%", logger_name="Dockerflow"):
         # positional arguments we have to do a version check here
         # to decide whether to pass the style argument or not.
         if sys.version_info[:2] < (3, 1):
-            parent_init(self, format, datefmt)
+            parent_init(self, fmt, datefmt)
         else:
-            parent_init(self, format, datefmt, style)
+            parent_init(self, fmt=fmt, datefmt=datefmt, style=style)
         self.logger_name = logger_name
         self.hostname = socket.gethostname()