Add main func in Gaussian aug unit tests

Author: Irina Nicolae

art/defences/gaussian_augmentation_unittest.py

@@ -35,3 +35,7 @@ def test_labels(self):
         self.assertTrue(new_x.shape[0] == new_y.shape[0] == 8)
         self.assertTrue(new_x.shape[1:] == x.shape[1:])
         self.assertTrue(new_y.shape[1:] == y.shape[1:])
+
+
+if __name__ == '__main__':
+    unittest.main()