Make signature of fake YoutubeDL.report_warning() match the real one …

…(per 640d39f)

test/test_download.py

@@ -54,7 +54,7 @@ def __init__(self, *args, **kwargs):
         self.processed_info_dicts = []
         super(YoutubeDL, self).__init__(*args, **kwargs)
 
-    def report_warning(self, message):
+    def report_warning(self, message, *args, **kwargs):
         # Don't accept warnings during tests
         raise ExtractorError(message)