Add missing xfail

Author: asmeurer

numpy-xfails.txt

@@ -42,6 +42,7 @@ array_api_tests/test_special_cases.py::test_iop[__ifloordiv__(isfinite(x1_i) and
 
 # https://github.com/numpy/numpy/issues/21213
 array_api_tests/test_special_cases.py::test_binary[__pow__(x1_i is -infinity and x2_i > 0 and not (x2_i.is_integer() and x2_i % 2 == 1)) -> +infinity]
+array_api_tests/test_special_cases.py::test_binary[__pow__(x1_i is -0 and x2_i > 0 and not (x2_i.is_integer() and x2_i % 2 == 1)) -> +0]
 array_api_tests/test_special_cases.py::test_iop[__ipow__(x1_i is -infinity and x2_i > 0 and not (x2_i.is_integer() and x2_i % 2 == 1)) -> +infinity]
 array_api_tests/test_special_cases.py::test_iop[__ipow__(x1_i is -0 and x2_i > 0 and not (x2_i.is_integer() and x2_i % 2 == 1)) -> +0]
 array_api_tests/meta/test_hypothesis_helpers.py::test_symmetric_matrices