Fix: missing 1 required positional argument: 'canvas' in Toolbar init

#488

Author: fleming79

ipympl/backend_nbagg.py

@@ -234,9 +234,7 @@ class Canvas(DOMWidget, FigureCanvasWebAggCore):
     current_dpi_ratio = 1.0
 
     def __init__(self, figure, *args, **kwargs):
-        DOMWidget.__init__(self, *args, **kwargs)
-        FigureCanvasWebAggCore.__init__(self, figure, *args, **kwargs)
-
+        super().__init__(canvas=canvas, **kwargs)
         self.on_msg(self._handle_message)
 
         # This will stay True for cases where there is no