gh-110686: Test pattern matching with runtime_checkable protocols

[sobolevn]

Port of python/cpython#110683

[AlexWaygood]

You'll need to make this change if you want the tests to pass on Python 3.12:

--- a/src/test_typing_extensions.py
+++ b/src/test_typing_extensions.py
@@ -5085,12 +5085,12 @@ class AllTests(BaseTestCase):
             exclude |= {'final', 'Any', 'NewType'}
         if sys.version_info < (3, 12):
             exclude |= {
-                'Protocol', 'SupportsAbs', 'SupportsBytes',
+                'SupportsAbs', 'SupportsBytes',
                 'SupportsComplex', 'SupportsFloat', 'SupportsIndex', 'SupportsInt',
                 'SupportsRound', 'Unpack',
             }
         if sys.version_info < (3, 13):
-            exclude |= {'NamedTuple', 'TypedDict', 'is_typeddict'}
+            exclude |= {'NamedTuple', 'Protocol', 'TypedDict', 'is_typeddict'}
         for item in typing_extensions.__all__:
             if item not in exclude and hasattr(typing, item):
                 self.assertIs(
diff --git a/src/typing_extensions.py b/src/typing_extensions.py
index cb3410e..b900335 100644
--- a/src/typing_extensions.py
+++ b/src/typing_extensions.py
@@ -506,7 +506,7 @@ def _caller(depth=2):

 # The performance of runtime-checkable protocols is significantly improved on Python 3.12,
 # so we backport the 3.12 version of Protocol to Python <=3.11
-if sys.version_info >= (3, 12):
+if sys.version_info >= (3, 13):
     Protocol = typing.Protocol
 else:
     def _allow_reckless_class_checks(depth=3):

I think a CHANGELOG entry would also be good :)