gh-137967: Fix "Whats New" doc example

Author: sobolevn

Doc/whatsnew/3.15.rst

@@ -190,10 +190,10 @@ Improved error messages
            return pi * self.radius**2
 
      class Container:
-        def __init__(self, inner: Any) -> None:
+        def __init__(self, inner: Circle) -> None:
            self.inner = inner
 
-     square = Square(side=4)
+     square = Circle(radius=4.0)
      container = Container(square)
      print(container.area)