python: Improve yapf formatting (#15587)

Signed-off-by: Ryan Northey <ryan@synca.io>

Mirrored from https://github.com/envoyproxy/envoy @ 83d0d992b508aec63b3ff830a40f2515acda80eb

tools/generate_listeners.py

@@ -58,8 +58,9 @@ def generate_listeners(listeners_pb_path, output_pb_path, output_json_path, frag
 
 if __name__ == '__main__':
     if len(sys.argv) < 4:
-        print('Usage: %s <path to listeners.pb> <output listeners.pb> <output '
-              'listeners.json> <filter config fragment paths>') % sys.argv[0]
+        print(
+            'Usage: %s <path to listeners.pb> <output listeners.pb> <output '
+            'listeners.json> <filter config fragment paths>') % sys.argv[0]
         sys.exit(1)
 
     generate_listeners(sys.argv[1], sys.argv[2], sys.argv[3], iter(sys.argv[4:]))