Fix cleanup of test_save_plot.py.

tests/test_save_plot.py

@@ -84,6 +84,7 @@ class TestSavePlot(unittest.TestCase):
         """
         with self.assertRaises(TypeError):
             save_plot([FIGURE, 'figure', FIGURE], 'PLOT_NAME', extension='jpg')
+        os.remove('PLOT_NAME1.jpg')
 
     def tearDown(self):
         os.remove(IMG1)