Remove PEP-604 methods from Sentinel on Python <3.10

We don't generally try to "backport PEP 604" on Python <3.10; this is more consistent with our features

Author: AlexWaygood

src/typing_extensions.py

@@ -4244,11 +4244,12 @@ def __repr__(self):
         def __call__(self, *args, **kwargs):
             raise TypeError(f"{type(self).__name__!r} object is not callable")
 
-    def __or__(self, other):
-        return typing.Union[self, other]
-
-    def __ror__(self, other):
-        return typing.Union[other, self]
+    if sys.version_info >= (3, 10):
+        def __or__(self, other):
+            return typing.Union[self, other]
+    
+        def __ror__(self, other):
+            return typing.Union[other, self]
 
     def __getstate__(self):
         raise TypeError(f"Cannot pickle {type(self).__name__!r} object")