trapezoidSideWall: Fix call to move

resulting in an assert error as the label was used as "before" parameter
which messes up the whole magic inside .move(). As a result the .stroke() method was not called - leading to unprocesses paths - triggering the assert.

Resolves: #423

boxes/__init__.py

@@ -2597,7 +2597,7 @@ class Boxes:
         edges[3](h0)
         self.edgeCorner(edges[-1], edges[0], 90)
 
-        self.move(overallwidth, overallheight, move, label)
+        self.move(overallwidth, overallheight, move, label=label)
 
     ### polygonWall and friends