TST: Fix runtime error checking NaN input to format_cursor_data

Author: QuLogic

lib/matplotlib/tests/test_image.py

@@ -1180,7 +1180,8 @@ def test_image_cursor_formatting():
     assert im.format_cursor_data(data) == '[0]'
 
     data = np.nan
-    assert im.format_cursor_data(data) == '[nan]'
+    with np.errstate(invalid='ignore'):
+        assert im.format_cursor_data(data) == '[nan]'
 
 
 @check_figures_equal(extensions=['png', 'pdf', 'svg'])