Test without warning suppression

Author: HexDecimal

src/typing_extensions.py

@@ -448,12 +448,9 @@ def __reduce__(self) -> str:
         """Reduce this sentinel to a singleton."""
         return self.__name__  # Module is taken from the __module__ attribute
 
-with warnings.catch_warnings():  # Allow sentinel subclass for backwards compatibility
-    warnings.simplefilter("ignore")
-
-    @deprecated("""Sentinel was renamed to typing_extensions.sentinel""")
-    class Sentinel(sentinel):
-        pass
+@deprecated("""Sentinel was renamed to typing_extensions.sentinel""")
+class Sentinel(sentinel):
+    pass
 
 _marker = sentinel("sentinel")