Remove redundant commas

Tried black version 21.7b0 on the original, and it wanted to add
even more brackets/commas.

Both black version 19.10b0 (currently version used in pre-commit)
and version 21.7b0 (latest release) like this simpler version.

Bio/Graphics/GenomeDiagram/_CircularDrawer.py

@@ -594,7 +594,7 @@ def draw_line_graph(self, graph):
                     strokeWidth=graph.linewidth,
                 )
             )
-            lastx, lasty, = x, y
+            lastx, lasty = x, y
         return line_elements
 
     def draw_bar_graph(self, graph):