fix weeird unit ests

Author: Jammy2211

test_autoarray/inversion/pixelization/mappers/test_rectangular.py

@@ -137,9 +137,9 @@ def test__edges_transformed(mask_2d_7x7):
 
     mapper = aa.Mapper(mapper_grids=mapper_grids, regularization=None)
 
-    assert mapper.edges_transformed[4] == pytest.approx(
+    assert mapper.edges_transformed[3] == pytest.approx(
         np.array(
             [1.5, 1.5],  # left
         ),
         abs=1e-8,
-    )
+    )