Add new line to EOF as per linting message.

Author: CharlesHe16

lib/matplotlib/tests/test_sankey.py

@@ -21,4 +21,4 @@ def show_three_decimal_places(value):
     s = Sankey(flows=[0.25], labels=['First'], orientations=[-1],
                format=show_three_decimal_places)
 
-    assert s.diagrams[0].texts[0].get_text() == 'First\n0.250'
+    assert s.diagrams[0].texts[0].get_text() == 'First\n0.250'