gh-141510: Update `test_xpickle` for `frozendict` (#144927)

Lib/test/pickletester.py

diff --git a/Lib/test/pickletester.py b/Lib/test/pickletester.py
index 5f627f0..c4460c2 100644
--- a/Lib/test/pickletester.py
+++ b/Lib/test/pickletester.py
@@ -3167,6 +3167,7 @@ def test_builtin_types(self):
             'bytes': (3, 0),
             'BuiltinImporter': (3, 3),
             'str': (3, 4),  # not interoperable with Python < 3.4
+            'frozendict': (3, 15),
         }
         for t in builtins.__dict__.values():
             if isinstance(t, type) and not issubclass(t, BaseException):