CI: revert skip of geopandas downstream test (pandas-dev#21217)

Author: jorisvandenbossche

pandas/tests/test_downstream.py

@@ -103,7 +103,6 @@ def test_pandas_datareader():
         'F', 'quandl', '2017-01-01', '2017-02-01')
 
 
-@pytest.mark.xfail(reaason="downstream install issue")
 def test_geopandas():
 
     geopandas = import_module('geopandas')  # noqa