Remove value attribute from builtins.StopAsyncIteration (#13275)

stdlib/builtins.pyi

@@ -1964,9 +1964,7 @@ class NameError(Exception):
 
 class ReferenceError(Exception): ...
 class RuntimeError(Exception): ...
-
-class StopAsyncIteration(Exception):
-    value: Any
+class StopAsyncIteration(Exception): ...
 
 class SyntaxError(Exception):
     msg: str