Mark test_idval_hypothesis as flaky on Windows (#3707)

testing/python/metafunc.py

@@ -212,6 +212,9 @@ class TestMetafunc(object):
     @hypothesis.settings(
         deadline=400.0
     )  # very close to std deadline and CI boxes are not reliable in CPU power
+    @pytest.mark.xfail(
+        sys.platform.startswith("win32"), reason="flaky #3707", strict=False
+    )
     def test_idval_hypothesis(self, value):
         from _pytest.python import _idval