gh-98713: Use @cpython_only for a test that fails on PyPy (GH-98714)

Co-authored-by: Alex Waygood <[email protected]>
(cherry picked from commit 9495360)

Co-authored-by: Nikita Sobolev <[email protected]>

Author: miss-islington

Lib/test/test_typing.py

@@ -42,7 +42,7 @@
 import weakref
 import types
 
-from test.support import import_helper, captured_stderr
+from test.support import import_helper, captured_stderr, cpython_only
 from test import mod_generics_cache
 from test import _typed_dict_helper
 
@@ -4615,6 +4615,7 @@ def blah():
 
         blah()
 
+    @cpython_only  # gh-98713
     def test_overload_on_compiled_functions(self):
         with patch("typing._overload_registry",
                    defaultdict(lambda: defaultdict(dict))):

Misc/NEWS.d/next/Tests/2022-10-26-15-19-20.gh-issue-98713.Lnu32R.rst

@@ -0,0 +1,3 @@
+Fix a bug in the :mod:`typing` tests where a test relying on CPython-specific
+implementation details was not decorated with ``@cpython_only`` and was not
+skipped on other implementations.