Update center bar label test.

Author: stefmolin

lib/matplotlib/tests/test_axes.py

@@ -7741,10 +7741,10 @@ def test_bar_label_location_center():
     ys, widths = [1, 2], [3, -4]
     rects = ax.barh(ys, widths)
     labels = ax.bar_label(rects, label_type='center')
-    assert labels[0].xy == (widths[0] / 2, ys[0])
+    assert labels[0].xy == (0.5, 0.5)
     assert labels[0].get_ha() == 'center'
     assert labels[0].get_va() == 'center'
-    assert labels[1].xy == (widths[1] / 2, ys[1])
+    assert labels[1].xy == (0.5, 0.5)
     assert labels[1].get_ha() == 'center'
     assert labels[1].get_va() == 'center'