TST: xfail statsmodels downstream test

xref gh-18362.

Author: gfyoung

pandas/tests/test_downstream.py

@@ -53,6 +53,7 @@ def test_xarray(df):
     assert df.to_xarray() is not None
 
 
+@pytest.mark.xfail(reason="statsmodels needs to remove reference to WidePanel")
 def test_statsmodels():
 
     statsmodels = import_module('statsmodels')  # noqa