Improve test_valid_complex_string_with_space() xfail condition

Improve the xfail condition for `test_valid_complex_string_with_space()`
to use PyPy version rather than Python version.  This corresponds
to the fact that the issue was fixed in 7.3.17 releases.  The other
condition works only because PyPy3.9 is no longer being developed,
and therefore did not get a 7.3.17 release.

Author: mgorny

tests/validators/test_complex.py

@@ -85,7 +85,7 @@ def test_complex_strict(input_value, expected):
 
 
 @pytest.mark.xfail(
-    platform.python_implementation() == 'PyPy' and sys.version_info < (3, 10),
+    platform.python_implementation() == 'PyPy' and sys.pypy_version_info < (7, 3, 17),
     reason='PyPy cannot process this string due to a bug, even if this string is considered valid in python',
 )
 def test_valid_complex_string_with_space():