test: mark xfail to DynamicClass

Author: XuehaiPan

tests/test_methods_and_attributes.py

@@ -364,6 +364,12 @@ class PythonDerivedDynamicClass(m.DynamicClass):
 
 # https://foss.heptapod.net/pypy/pypy/-/issues/2447
 @pytest.mark.xfail("env.PYPY")
+@pytest.mark.xfail(
+    sys.version_info == (3, 14, 0, "beta", 1)
+    or sys.version_info == (3, 14, 0, "beta", 2),
+    reason="3.14.0b1/2 bug: https://github.com/python/cpython/issues/133912",
+    strict=False,
+)
 @pytest.mark.skipif("env.GRAALPY", reason="Cannot reliably trigger GC")
 def test_cyclic_gc():
     # One object references itself